ORCID Profile
0000-0003-0525-2795
Current Organisation
Curtin University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Physical Chemistry (Incl. Structural) | Chemical Spectroscopy | Chemical Thermodynamics And Energetics | Fluidization And Fluid Mechanics | Theoretical and Computational Chemistry | Quantum Chemistry | Structural Chemistry and Spectroscopy | Supramolecular Chemistry | Physical Chemistry Not Elsewhere Classified | Interdisciplinary Engineering Not Elsewhere Classified | Medicinal and Biomolecular Chemistry | Biological And Medical Chemistry | Characterisation Of Macromolecules | Mechanisms Of Reactions | Non-automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels) | Biochemistry and Cell Biology not elsewhere classified | Instruments And Techniques | Optical Physics Not Elsewhere Classified | Theoretical And Computational Chemistry Not Elsewhere Classified | Physical Chemistry not elsewhere classified | Analytical Chemistry Not Elsewhere Classified | Genome Structure | Theoretical Physics | Interdisciplinary Engineering |
ANZSRC Socio-Economic Objective (SEO)
Chemical sciences | Physical sciences | Scientific instrumentation | Expanding Knowledge in the Chemical Sciences | Higher education | Medical instrumentation | Production of Biofuels (Biomass) | Biological sciences | Computer software and services not elsewhere classified | Field crops not elsewhere classified | Water services and utilities | Clinical health not specific to particular organs, diseases and conditions | Expanding Knowledge in the Biological Sciences
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Publications
UV–Vis and fluorimetric Al3+, Zn2+, Cd2+ and Pb2+ complexation studies of two 3-hydroxyflavones and a 3-hydroxythioflavone
Publisher: Elsevier BV
Date: 07-2007
Photoionization of Nb3CO and Nb3(CO)2: Is CO Molecularly or Dissociatively Adsorbed on Niobium?
Publisher: American Chemical Society (ACS)
Date: 16-01-2004
DOI: 10.1021/JP036041+
Structural Variation in Diorganotin Dimethylxanthates, R2Sn(S2COMe)2: A Combined Crystallographic and Theoretical Investigation
Publisher: American Chemical Society (ACS)
Date: 15-11-2000
DOI: 10.1021/OM000717V
A disconnect between staff and student perceptions of learning: An ACELL educational analysis of the first year undergraduate chemistry experiment 'investigating sugar using a home made polarimeter'
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0RP90015J
The timing of an experiment in the laboratory program is crucial for the student laboratory experience: acylation of ferrocene as a case study
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3RP00011G
Time-of-flight mass spectrometric detection of mono- and di-substituted benzenes at parts per million concentrations by way of liquid microjet injection and laser ionisation
Publisher: Elsevier BV
Date: 04-2001
Infrared Laser Desorption of Hydroquinone from a Water−Ethanol Liquid Beam
Publisher: American Chemical Society (ACS)
Date: 19-07-2003
DOI: 10.1021/JP022248B
Surface movement in water of splendipherin, the aquatic male sex pheromone of the tree frog Litoria splendida
Publisher: Wiley
Date: 28-06-2008
DOI: 10.1111/J.1742-4658.2008.06483.X
Abstract: The aquatic sex pheromone splendipherin (GLVSSIGKALGGLLADVVKSKGQPA-OH) of the male green tree frog Litoria splendida moves across the surface of water to reach the female. Surface pressure and X-ray reflectometry measurements confirm that splendipherin is a surface-active molecule, and are consistent with it having an ordered structure, whereby the hydrophilic portion of the peptide interacts with the underlying water and the hydrophobic region is adjacent to the vapour phase. The movement of splendipherin over the surface of water is caused by a surface pressure gradient. In order to better define the structure of splendipherin at the water/air interface we used 2D NMR studies of the pheromone with the solvent system trifluoroethanol/water (1 : 1 v/v). In this solvent system, splendipherin adopts a bent alpha helix from residues V3 to K21. The bending of the helix occurs in the centre of the peptide in the vicinity of G11 and G12. The region of splendipherin from V3 to G11 has well-defined hipathicity, whereas the hipathicity from G12 to A25 is reduced by K19 and P24 intruding into the hydrophobic and hydrophilic regions respectively. A helical structure is consistent with X-ray reflectometry data.
Translational and rotational energy content of benzene molecules IR-desorbed from an in vacuo liquid surface
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CP40180K
Abstract: Benzene molecules were desorbed from an in vacuo aqueous liquid beam by direct irradiation of the beam with an IR laser tuned to the 2.85 μm absorption band of water. Spectroscopic interrogation of the desorbed benzene molecules was performed via 1 + 1 Resonance-Enhanced Multi-photon Ionisation (REMPI). Rotational contour analyses of the 6 vibronic transition of benzene were performed to determine the rotational temperature of those molecules ejected during the desorption event. At the peak of the desorption plume density, the rotational temperatures were found to be up to ∼100 K lower than that recorded for molecules spontaneously evaporating from the liquid surface. At longer IR-UV laser delay times the benzene rotational temperatures are found to return to those observed following spontaneous evaporation. No evidence of IR desorbed neutral or cationic benzene-containing clusters was observed. However, ionic clusters were observed to be formed after REMPI of the benzene monomer. Analysis of the benzene intensity and that of post-REMPI formed clusters as a function of IR-UV delay shows that number density and local translational temperature vary along the desorption plume.
Regioselective control of the nickel-mediated coupling of acetylene and carbon dioxide – A DFT study
Publisher: Elsevier BV
Date: 08-2008
DFT Calculations on Group 5 Mixed Metal Tetramers: TaxNbyVz (x + y + z = 4)
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/CH04122
Abstract: We report Density Functional Theory (DFT) calculations on mixed-metal tetramers comprised of the Group 5 (Vb) elements V, Nb, and Ta. Our results show that the lowest energy structures for Nb4 and Ta4 are regular tetrahedra with Td symmetry and singlet multiplicity whereas V4 is a triplet state with C2v symmetry. The monosubstituted isomers, A3B, all have C3v symmetry but several higher energy Cs structures have been found that are approximately 100 kJ mol−1 higher in energy. The disubstituted isomers all posses arachno-butterfly structures the A2B2 types with C2v symmetry and the A2BC types with Cs symmetry. However, the relative openness of the arachno structures is found to be specific to the composition of the mixed-metal cluster.
Study of the Isomers of Isoelectronic C-4, (C3B)(-), and (C3N)(+): Rearrangements through Cyclic Isomers
Publisher: American Chemical Society (ACS)
Date: 09-10-2009
DOI: 10.1021/JP907484Z
Abstract: Optimized structures of the isoelectronic cumulenes (CCCB)(-), CCCC, and (CCCN)(+) and of their isomers formed by rearrangement have been calculated at the B3LYP/6-311+ G(3df) level of theory with relative energies and electronic states determined at the CCSD(T)/aug-cc-pVTZ level of theory. The ground states of CCCC and (CCCN)(+) are triplets, whereas the ground state of (CCCB)(-) is a quasi-linear singlet structure that is only 0.6 kcal mol(-1) more negative in energy than the linear triplet. When energized, both triplet and singlet CCCC cyclize to planar rhomboids, of which the singlet is the lowest-energy configuration. Ring-opening of rhomboid C(4) reforms CCCC with the carbons partially randomized. Similar rearrangements occur for (CCCB)(-) and (CCCN)(+), but the reactions are different in the detail. In the case of (CCCN)(+), rearrangement of atoms is supported both experimentally and theoretically. Because (CCCB)(-) and (CCCN)(+) are not symmetrical, two fully cyclized forms are possible the one more resembling a rhomboid structure is called a "kite" structure, and the other is called a "fan" structure. The rearrangement of (CCCB)(-) is more favored via the triplet with equilibrating kite and fan structures being formed, whereas the singlet (CCCN)(+) ring closes to give the singlet kite structure, which may ring open to give a mixture of (CCCN)(+) and (CCNC)(+). Intersystem crossing may occur for the triplet and singlet forms of CCCC and (CCCB)(-) but not for (CCCN)(+).
Threshold Photoionization and Density Functional Theory Studies of the Niobium Carbide Clusters Nb3Cn (n = 1−4) and Nb4Cn (n = 1
Publisher: American Chemical Society (ACS)
Date: 06-2008
DOI: 10.1021/JP800691S
Abstract: We have used photoionization efficiency spectroscopy to determine ionization potentials (IP) of the niobium-carbide clusters, Nb3C(n) (n = 1-4) and Nb4C(n) (n = 1-6). The Nb3C2 and Nb4C4 clusters exhibit the lowest IPs for the two series, respectively. For clusters containing up to four carbon atoms, excellent agreement is found with relative IPs calculated using density functional theory. The lowest energy isomers are mostly consistent with the development of a 2 x 2 x 2 face-centered cubic structure of Nb4C4. However, for Nb3C4 a low-lying isomer containing a molecular C2 unit is assigned to the experimental IP rather than the depleted 2 x 2 x 2 nanocrystal isomer. For Nb4C5 and Nb4C6, interpretation is less straightforward, but results indicate isomers containing molecular C2 units are the lowest in energy, suggesting that carbon-carbon bonding is preferred when the number of carbon atoms exceeds the number of metal atoms. A double IP onset is observed for Nb4C3, which is attributed to ionization from the both the lowest energy singlet state and a meta-stable triplet state. This work further supports the notion that IPs can be used as a reliable validation for the geometries of metal-carbide clusters calculated by theory.
Measuring the internal energy content of molecules transported across the liquid-gas interface
Publisher: IOP Publishing
Date: 09-2009
Jet-Cooled Multiphoton Ionization Spectroscopy of the iso-Butanal 3s←n Rydberg Transition
Publisher: Elsevier BV
Date: 03-2001
On the structure of the monohydrated superoxide molecular anion, O2-·(H2O). An ab initio molecular orbital study
Publisher: Royal Society of Chemistry (RSC)
Date: 1999
DOI: 10.1039/A904184B
Structure of the Molecular Receptor 1,4,7,10-Tetrakis[(S)-2-hydroxy-2-phenylethyl]-1,4,7,10-tetraazacyclododecane: A Combined X-Ray Crystallographic and Theoretical Study Producing an Assessment of th
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/CH05275
Abstract: X-Ray crystallography demonstrates that the guest molecule binding cavity within the molecular receptor ligand 1,4,7,10-tetrakis[(S)-2-hydroxy-2-phenylethyl]-1,4,7,10-tetraazacyclododecane, (S)-thpec12, is a poorly defined conical region stabilized by three O–H···O hydrogen bonds and a single O–H···N hydrogen bond. Two similar, but crystallographically independent, molecules exist within the unit cell. Ab initio calculations, using Gaussian 03 (LanL2DZ basis set at the Hartree–Fock level of theory), predict that these have steric energies of 97.73 and 97.06 kJ mol−1, respectively, above that of the minimum energy (gas phase) conformer of the same hydrogen-bonding configuration, which is believed to be the structure of global minimum energy. The mean of these energies (97.4 kJ mol−1) represents a best estimate of the crystal packing energy for (S)-thpec12, some of which is seen to be expended in rotating the phenyl rings away from the positions favoured in the gas phase. The ability of the CdII complex of (S)-thpec12 to act as a molecular receptor for aromatic anions is demonstrated by the isolation of two inclusion compounds in which p-nitrophenolate and anthraquinone-2-sulfonate are retained.
Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4′-oxyazobenzene: UV-visible,1H NMR and ab initio studies
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B415594G
Abstract: alpha-Cyclodextrin, beta-cyclodextrin, N-(6(A)-deoxy-alpha-cyclodextrin-6(A)-yl)-N'6(A)-deoxy-beta-cyclodextrin-6(A)-yl)urea and N,N-bis(6(A)-deoxy-beta-cyclodextrin-6(A)-yl)urea (alphaCD, betaCD, 1 and 2) form inclusion complexes with E-4-tert-butylphenyl-4'-oxyazobenzene, E-3(-). In aqueous solution at pH 10.0, 298.2 K and I = 0.10 mol dm(-3)(NaClO(4)) spectrophotometric UV-visible studies yield the sequential formation constants: K(11) = (2.83 +/- 0.28) x 10(5) dm(3) mol(-1) for alphaCD.E-(-), K(21) = (6.93 +/- 0.06) x 10(3) dm(3) mol(-1) for (alphaCD)(2).E-3(-), K(11) = (1.24 +/- 0.12) x 10(5) dm(3) mol(-1) for betaCD.E-(-), K(21) = (1.22 +/- 0.06) x 10(4) dm(3) mol(-1) for (betaCD)(2).E-(-), K(11) = (3.08 +/- 0.03) x 10(5) dm(3) mol(-1) for .E-3(-), K(11) = (8.05 +/- 0.63) x 10(4) dm(3) mol(-1) for .E-3(-) and K(12) = (2.42 +/- 0.53) x 10(4) dm(3) mol(-1) for .(E-3(-))(2). (1)H ROESY NMR studies show that complexation of E-3(-) in the annuli of alphaCD, betaCD, 1 and 2 occurs. A variable-temperature (1)H NMR study yields k(298 K)= 6.7 +/- 0.5 and 5.7 +/- 0.5 s(-1), DeltaH = 61.7 +/- 2.7 and 88.1 +/- 4.2 kJ mol(-1) and DeltaS = -22.2 +/- 8.7 and 65 +/- 13 J K(-1) mol(-1) for the interconversion of the dominant includomers (complexes with different orientations of alphaCD) of alphaCD.E-3(-) and (alphaCD)(2).E-3(-), respectively. The existence of E-3(-) as the sole isomer was investigated through an ab initio study.
Gas phase ion formation from a liquid beam of arginine in aqueous solution by IR multiphoton excitation
Publisher: Elsevier BV
Date: 03-2006
Metal ion-activated molecular receptors for aromatic anions with receptor cavities formed from 1- or 2-naphthyloxy moieties appended to cyclen
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B305461F
The dynamics of evaporation from a liquid surface
Publisher: Elsevier BV
Date: 09-2011
What Makes a Good Laboratory Learning Exercise? Student Feedback from the ACELL Project
Publisher: Springer Netherlands
Date: 2009
Development, Evaluation and Use of a Student Experience Survey in Undergraduate Science Laboratories: The Advancing Science by Enhancing Learning in the Laboratory Student Laboratory Learning Experience Survey
Publisher: Informa UK Limited
Date: 16-06-2015
Diastereomeric 1,4,7,10-Tetrakis((S)-2-hydroxypropyl)- 1,4,7,10-tetraazacyclododecane and Its Alkali Metal Complex Ions. A Nuclear Magnetic Resonance, Potentiometric Titration, and Molecular Or
Publisher: American Chemical Society (ACS)
Date: 07-1997
DOI: 10.1021/JA9702071
Ligand-Mediated Control of the Surface Oxidation States of Copper Nanoparticles Produced by Laser Ablation
Publisher: American Chemical Society (ACS)
Date: 30-03-2023
Influence of Surfactant Concentration on Laser-Based Gold Nanoparticle Formation and Stability
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH11366
Abstract: The time evolution of gold nanoparticle (AuNP) yields by in-situ laser irradiation from bulk gold in aqueous solutions containing the surfactant sodium dodecylsulfate (SDS) at concentrations above and below the critical micelle concentration in water is reported. These studies are augmented by transmission electron microscopy images of AuNP s les at each SDS concentration recorded after 90 min of laser irradiation. The results show that while a low concentration of SDS plays a role in the formation kinetics, there is no apparent influence of the SDS concentration around the surfactant critical micelle concentration on particle size during AuNP production.
Some ruthenium complexes containing cyanocarbon ligands: syntheses, structures and extent of electronic communication in binuclear systems
Publisher: Elsevier BV
Date: 10-2004
Photoreduction Kinetics of Sodium Tetrachloroaurate under Synchrotron Soft X-ray Exposure
Publisher: American Chemical Society (ACS)
Date: 08-06-2011
DOI: 10.1021/LA200463K
Abstract: We report on the time evolution of the sodium tetrachloroaurate (NaAuCl(4)) chemical properties as a function of soft X-ray exposure in a dried s le on a silicon surface using X-ray photoelectron spectroscopy (XPS). Our investigations provide mechanistic insight into the photoreduction kinetics from Au(III) to Au(I) and then Au(I) to Au(0). We unambiguously show that XPS photoreduction occurs in stepwise fashion via the Au(I) state. Both photoreduction steps undergo first-order kinetics.
Collisional electrochemistry of laser-ablated gold nanoparticles by electrocatalytic oxidation of glucose
Publisher: Elsevier BV
Date: 04-2017
Associative Versus Dissociative Binding of CO to 4d Transistion Metal Trimers: A Density Functional Study
Publisher: Wiley
Date: 04-04-2008
DOI: 10.1002/JCC.20912
Abstract: Density functional calculations were performed to determine equilibrium geometrical structures, transition states and relative energies for M(3) clusters (M = Nb, Mo, Tc, Ru, Rh, Pd, Ag) reacting with CO, leading to proposed reaction pathways. For the Nb(3), Mo(3), and Tc(3) clusters, the lowest energy structure correlates to dissociated CO, with the C and O atoms bound on opposite sides of the metal triangle. For all other trimers, the lowest energy structures maintain the CO moiety. In the case of Pd(3) and Ag(3) the dissociated geometries lie higher in energy than the sum of the separated reactants. In most cases, several multiplicities were found to be similar in energy and for Mo(3)CO and Pd(3)CO singlet-triplet minimum energy crossing points were identified. In the case of Rh(3)CO, minimum energy crossing points for the doublet, quartet, and sextet reaction pathways were determined and compared. The electron densities of pertinent M(3)CO species were investigated using Natural Bond Order calculations. It was found that the effect of the metal trimer on the energy of the pure p-type pi* antibonding orbital of carbon monoxide directly correlates with the occurrence of CO dissociation.
Reaction rate constants for singlet silylene and singlet germylene with water, methanol, ethanol, dimethyl ether and trifluoromethanol: Competition between H-atom migration and H2 elimination
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/CH01040
Examination of the effect of crystal packing forces on geometric parameters: A combined crystallographic and theoretical study of 2,2′-bipyridyl adducts of R2 SnCl2
Publisher: Walter de Gruyter GmbH
Date: 2000
DOI: 10.1524/ZKRI.2000.215.1.23
Abstract: Crystal structure determinations on a series of R 2 SnCl 2 (bipy)[bipy is 2,2'-bipyridyl] compounds show that these adopt a common structural motif in the solid-state with the Sn-bound organic substituents occupying mutually trans positions in a distorted octahedral geometry. A comparison of the experimental Sn–Cl and Sn–N bond distances with the moderated (i.e. by changing the nature of R) Lewis acidities of the tin atoms shows a general correlation, i.e. longer distances with decreasing Lewis acidity, but with a relatively large spread of values. In order to examine the role of crystal packing effects on the derived geometric parameters, gas-phase structures for these compounds have been modeled employing ab initio molecular orbital theory. These calculations showed that within in idual compounds the two Sn–Cl distances are equal as are the two Sn–N distances, in contrast to the solid-state results. Further, a better correlation between the Sn–Cl and Sn–N bond distances and the Lewis acidity of the tin atom was found. These key results are attributed to the influence of crystal packing forces on the geometric parameters about the tin center in the solid-state.
Onset of carbon–carbon bonding in the Nb5Cy(y = 0–6) clusters: a threshold photo-ionisation and density functional theory study
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B813359J
Abstract: We have used photo-ionisation efficiency spectroscopy to determine the ionisation potentials (IPs) of the niobium-carbide clusters, Nb(5)C(y) (y = 0-6). Of these clusters Nb(5)C(2) and Nb(5)C(3) exhibit the lowest IPs. Complementary density functional theory calculations have been performed to locate the lowest energy isomers for each cluster. By comparing the experimental IPs with those calculated for candidate isomers, the structures of the Nb(5)C(y) clusters observed in the experiment are inferred. For all these structures, the underlying Nb(5) cluster has either a "prolate" or "oblate" trigonal bipyramid geometry. Both Nb(5)C(5) and Nb(5)C(6) are shown to contain carbon-carbon bonding in the form of one and two molecular C(2) units, respectively.
Supramolecular Sn⋯Cl associations in diorganotin dichlorides and their influence on molecular geometry as studied by ab initio molecular orbital calculations
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B308922C
Ultraviolet Laser Irradiation of Low Concentration Liquid Microjets: Solute Evaporation and Solvent Initiated Reactivity
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/CH03011
Abstract: Resonance-enhanced 266 nm 1 + 1 multiphoton ionization has been used in conjunction with a liquid microjet time-of-flight mass spectrometer to explore the photochemistry of a 10–3 M solution of anisole in ethanol. Only ions generated in the condensed phase originating from the three-photon non-resonant ionization of the ethanol solvent are liberated into the vacuum. No solute ions generated in solution are observed unless the concentration is increased to 1 M. Under high concentration conditions, solute pairing or aggregation at the liquid surface is a necessary precursor towards liberating solute photoions into the vacuum via a Coulombic explosion. At a solution concentration of 10–3 M, a decreased solute ion density at the liquid surface is insufficient to initiate a Coulombic explosion into the vacuum. Rather, non-resonantly generated solvent ions on the liquid surface dominate the ion ejection process. Related studies on 10–3 M solutions of 4-methoxyphenol in both ethanol and water show that at this concentration solute ionization is most likely to be observed following thermal evaporation from the surface of a liquid beam.
Perceptions and Misconceptions about the Undergraduate Laboratory from Chemistry, Physics and Biology Academics
Publisher: The University of Sydney Library
Date: 31-12-2020
DOI: 10.30722/IJISME.28.04.001
Abstract: The undergraduate laboratory occupies a large fraction of science students’ time. Over 3000 students were asked to rate their laboratory learning experience using 12 metrics. 362 academics were asked to predict which of these 12 aspects of the student experience would correlate with the overall laboratory learning experience. Responses from academics in biology, chemistry and physics departments, and from the USA and Australia, are statistically the same. However, the correlation between these staff predictions and student results is poor. The student results are consistent with extant educational research, but it appears that these findings are not reaching those who are responsible for developing undergraduate laboratory courses. There is a great need for educational research to be made more accessible for academics who are trained in scientific, but not in educational research.
Diastereomeric preference in 1,4,7-tris((S)-2-hydroxy-3-phenylpropyl)-1,4,7-triazacyclononanelithium(I) and its sodium(I) analogue
Publisher: Elsevier BV
Date: 03-2002
Production of Acrylic Acid through Nickel-Mediated Coupling of Ethylene and Carbon Dioxide—A DFT Study
Publisher: American Chemical Society (ACS)
Date: 27-11-2007
DOI: 10.1021/OM700592W
Synthesis and coordination chemistry of 1,4,7,10,13-pentakis(2-hydroxyethyl)-1,4,7,10,13-pentaazacyclopentadecane: a five armed pendant donor macrocycle
Publisher: Royal Society of Chemistry (RSC)
Date: 20-08-2002
DOI: 10.1039/B205700J
Ab initio calculations of stationary points on the benzene–Ar and p-difluorobenzene–Ar potential energy surfaces: barriers to bound orbiting states
Publisher: AIP Publishing
Date: 23-08-2004
DOI: 10.1063/1.1772355
Abstract: The potential energy surfaces of the van der Waals complexes benzene–Ar and p-difluorobenzene–Ar have been investigated at the second-order Møller–Plesset (MP2) level of theory with the aug-cc-pVDZ basis set. Calculations were performed with unconstrained geometry optimization for all stationary points. This study has been performed to elucidate the nature of a conflict between experimental results from dispersed fluorescence and velocity map imaging (VMI). The inconsistency is that spectra for levels of p-difluorobenzene–Ar and –Kr below the dissociation thresholds determined by VMI show bands where free p-difluorobenzene emits, suggesting that dissociation is occurring. We proposed that the bands observed in the dispersed fluorescence spectra are due to emission from states in which the rare gas atom orbits the aromatic chromophore these states are populated by intramolecular vibrational redistribution from the initially excited level [S. M. Bellm, R. J. Moulds, and W. D. Lawrance, J. Chem. Phys. 115, 10709 (2001)]. To test this proposition, stationary points have been located on both the benzene–Ar and p-difluorobenzene–Ar potential energy surfaces (PESs) to determine the barriers to this orbiting motion. Comparison with previous single point CCSD(T) calculations of the benzene–Ar PES has been used to determine the amount by which the barriers are overestimated at the MP2 level. As there is little difference in the comparable regions of the benzene–Ar and p-difluorobenzene–Ar PESs, the overestimation is expected to be similar for p-difluorobenzene–Ar. Allowing for this overestimation gives the barrier to movement of the Ar atom around the pDFB ring via the valley between the H atoms as ⩽204 cm−1 in S0 (including zero point energy). From the estimated change upon electronic excitation, the corresponding barrier in S1 is estimated to be ⩽225 cm−1. This barrier is less than the 240 cm−1 energy of 302¯, the vibrational level for which the anomalous “free p-difluorobenzene” bands were observed in dispersed fluorescence from p-difluorobenzene–Ar, supporting our hypothesis for the origin of these bands.
The (n, 3s) Rydberg State in Deuterated Aldehydes: Jet-Cooled MPI Spectra of the sym and asym Rotamers of CHD2CHO and CDH2CHO
Publisher: Elsevier BV
Date: 05-1994
Ionization Potentials of Tantalum−Carbide Clusters: An Experimental and Density Functional Theory Study
Publisher: American Chemical Society (ACS)
Date: 16-11-2005
DOI: 10.1021/JP054410R
Abstract: We have used photoionization efficiency spectroscopy to determine the ionization potentials (IP) of the tantalum-carbide clusters, Ta3Cn (n = 1-3) and Ta4Cn (n = 1-4). The ionization potentials follow an overall reduction as the number of carbon atoms increases however, the trend is not steady as expected from a simple electrostatic argument. Instead, an oscillatory behavior is observed such that clusters with an odd number of carbon atoms have higher IPs and clusters with an even number of carbon atoms have lower IPs, with the Ta4C4 cluster exhibiting the lowest IP. Excellent agreement is found with relative IPs calculated using density functional theory for the lowest energy structures, which are consistent with the development of a 2 x 2 x 2 face-centered nanocrystal. This work shows that IPs may be used as a reliable validation for the geometries of metal-carbide clusters calculated by theory. The variation in IP can also be interpreted qualitatively with application of a simple model based upon isolobal frontier orbitals.
The (n, 3s) Rydberg State in Deuterated Aldehydes: Jet-Cooled MPI Spectra of the Propanal Isotopomeric Series
Publisher: Elsevier BV
Date: 05-1994
Rotational Energy Distributions of Benzene Liberated from Aqueous Liquid Microjets: A Comparison between Evaporation and Infrared Desorption
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/CH05319
Abstract: We have measured the rotational energy distribution of benzene molecules both evaporated and desorbed by an IR laser from a liquid microjet. Analysis of the 601 vibronic band of benzene has shown that the benzene molecules evaporating from the liquid microjet surface have a rotational temperature of 157 ± 7 K. In contrast, the rotational temperature of benzene molecules desorbed from the liquid microjet by a 1.9 μm laser pulse is 82 ± 5 K. However, in both cases careful inspection of the spectral profiles shows that the experimental rotational distributions are non-Boltzmann, displaying an underpopulation of high rotational states and a relative overpopulation of the low rotational states. The non-equilibrium evaporation and desorption spectral profiles are consistent with a model that involves transfer of internal energy into translation upon liberation from the condensed phase.
Photoionization efficiency spectroscopy and density functional theory investigations of RhHo2On (n=–2) clusters
Publisher: AIP Publishing
Date: 28-04-2009
DOI: 10.1063/1.3120442
Abstract: The experimental and theoretical adiabatic ionization energies (IEs) of the rhodium-holmium bimetallic clusters RhHo2On (n=0–2) have been determined using photoionization efficiency spectroscopy and density functional theory (DFT) calculations. Both sets of data show the IE of RhHo2O to be significantly lower than the values for RhHo2 and RhHo2O2, which are found to be similar. This indicates that there are significant changes in electronic properties upon sequential addition of oxygen atoms to RhHo2. The DFT investigations show that the lowest energy neutral structures are a C2v triangle for RhHo2, a C2v planar structure for RhHo2O where the O atom is doubly bridged to the Ho–Ho bond, and a C2v nonplanar structure for RhHo2O2, where the O2 is dissociative and each O atom is doubly bridged to the Ho–Ho bond in the cluster above and below the RhHo2 trimer plane. Good correlation between the experimental and computational IE data imply that the lowest energy neutral structures calculated are the most likely isomers ionized in the molecular beam. In particular, the theoretical adiabatic IE for the dissociative RhHo2O2 structure is found to compare better with the experimentally determined value than the corresponding lowest energy O2 associative structure.
The lowest-lying excited singlet and triplet electronic states of propanal: an ab initio molecular orbital investigation of the potential energy surfaces
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B313777E
Laser-Based Formation and Properties of Gold Nanoparticles in Aqueous Solution: Formation Kinetics and Surfactant-Modified Particle Size Distributions
Publisher: American Chemical Society (ACS)
Date: 17-05-2010
DOI: 10.1021/JP9118315
Diastereomeric Δ-1,4,7,10-Tetrakis((R)-2-hydroxy-2-phenylethyl)- 1,4,7,10-tetraazacyclododecane and Its Alkali-Metal Complex Ions. A Potentiometric Titration, Nuclear Magnetic Resonance, and Mo
Publisher: American Chemical Society (ACS)
Date: 11-03-1998
DOI: 10.1021/JA973367L
Facile Decarboxylation of Propiolic Acid on a Ruthenium Center and Related Chemistry
Publisher: American Chemical Society (ACS)
Date: 08-2012
DOI: 10.1021/OM300157W
Influence of Cationic Surfactants on the Formation and Surface Oxidation States of Gold Nanoparticles Produced via Laser Ablation
Publisher: American Chemical Society (ACS)
Date: 24-09-2013
DOI: 10.1021/LA402234K
Abstract: We report on the time evolution of gold nanoparticles produced by laser ablation in the presence of the cationic surfactants cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC) in aqueous solution. The broader applicability of a laser-induced nanoparticle formation kinetic model previously developed by us for the case of anionic surfactants in aqueous solution [ J. Phys. Chem. C 2010 , 114 , 15931 - 15940 ] is shown to also apply in the presence of cationic surfactants. We explore the surface properties of the nanoparticles produced in the presence of the cationic surfactants via synchrotron X-ray photoelectron spectroscopy (XPS). The XPS data indicate that at CTA(+) concentrations approximating the aqueous critical micelle concentration Au(III) is present on the nanoparticle surface. Such oxidation is not observed at (i) lower CTA(+) concentrations, (ii) in the presence of an anionic surfactant, or (iii) in the case of pure water as a solvent.
Anion-π interactions of hexaaryl[3]radialenes
Publisher: American Chemical Society (ACS)
Date: 19-07-2012
DOI: 10.1021/JP301464S
Abstract: Coordination polymers and discrete metallo-supramolecular assemblies of hexaaryl[3]radialene compounds exhibit intriguing structures with short anion to π-centroid distances in the solid-state. Furthermore, these [3]radialene compounds display useful photophysical and electrochemical properties that make them ideal as potential platforms for anion receptors. In this study, hexafluoro[3]radialene was optimized to the MP2/aug-cc-pVTZ level of theory, and its complexes with halide anions were optimized to HF/6-31G++(d,p), MP2/6-31G++(d,p), M06-2X/6-31G++(d,p), and M06-2X/6-311G++(d,p) levels of theory. Hexafluoro[3]radialene was shown to have properties (large positive Qzz and areas of positive electrostatic surface potential) comparable to other compounds that show anion-π interactions. The interaction energies of complexes of hexafluoro[3]radialene with halide anions were calculated and found to be favorable and equivalent to those of fluorinated aromatic compounds. A series of synthetically accessible hexaaryl[3]radialenes were optimized to HF/6-31G++(d,p) theory and their complexes with halides optimized to the M06-2X/6-31G++(d,p) level of theory. The calculated properties of the electron-deficient hexaaryl[3]radialenes also show large positive Qzz quadrupole moments and two areas of positive potential at the [3]radialene core and the acidic aryl hydrogen atoms. The interaction energies of the complexes of hexaaryl[3]radialenes and halide anions were found to follow the trend F(-) > Cl(-) ≈ Br(-) and correlate with the electron-deficient nature of the [3]radialene. Close contacts were observed between the anion and the radialene core and the aryl hydrogen atoms, suggesting a combination of anion-π and hydrogen bonding is important. Mass spectrometry was used to experimentally observe the complexes of a number of hexaaryl[3]radialenes with F(-), Cl(-), and Br(-) predicted computationally. Anion-[3]radialene complexes were successfully detected, and the stability of the complexes in tandem MS/MS experiments was found to support the computational results.
BFW: A Density Functional for Transition Metal Clusters
Publisher: American Chemical Society (ACS)
Date: 14-03-2007
DOI: 10.1021/JP067752L
Abstract: Ionization potentials (IPs) or electron affinities (EAs) for transition metal clusters are an important property that can be used to identify and differentiate between clusters. Accurate calculation of these values is therefore vital. Previous attempts using a variety of DFT models have correctly predicted trends, but have relied on the use of scaling factors to compare to experimental IPs. In this paper, we introduce a new density functional (BFW) that is explicitly designed to yield accurate, absolute IPs for transition metal clusters. This paper presents the numerical results for a selection of transition metal clusters and their carbides, nitrides, and oxides for which experimental IPs are known. When tested on transition metal clusters, the BFW functional is found to be significantly more accurate than B3LYP and B3PW91.
Benzene Internal Energy Distributions Following Spontaneous Evaporation from a Water−Ethanol Solution
Publisher: American Chemical Society (ACS)
Date: 19-12-2008
DOI: 10.1021/JP804270V
Crystal structure of anhydrous potassium O-n-propyldithiocarbonate. Theoretical calculations of O-alkyl dithiocarbonates
Publisher: Walter de Gruyter GmbH
Date: 2003
DOI: 10.1524/ZKRI.218.1.56.20767
Abstract: The xanthate anion in the structure of K[S 2 COnPr] displays the expected features, i.e. planar S 2 CO chromophore and variation in C—S and C—O distances. The K cation exists in a distorted cubic geometry defined by an O 2 S 6 donor set. Cubes are face-shared so as to form a layer structure with cohesion between layers afforded by hydrophobic interactions. A series of theoretical gas-phase structures have been calculated for isolated S 2 COR anions. These show that there is a remarkable consistency in geometric parameters across the series. This observation indicates that the nature of the R substituent does not influence greatly the electronic structure of the central S 2 CO chromophore.
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