Robert Benny Gerber

• University of California, Irvine

Products of the oxidation of BTH by OH in air.

The highly reactive dihalogens play a significant role in the oxidative chemistry of the troposphere. One of the main reservoirs of these halogens is hypohalous acids, HOX, which produce dihalogens in the presence of halides (Y–), where X, Y = Cl, Br, I. These reactions occur in and on aerosol particles and seawater surfaces and have been studied e...

The Cover Feature shows the nighttime reactions of dinitrogen pentoxide (N2O5) with chloride (Cl−) and water at the surface of sea spray aerosols. In this work we identify 3 reaction mechanisms in the competition between Cl− substitution and hydrolysis of N2O5 via quantum chemical and dynamics studies of model clusters. The competition of these rea...

We report vibrational spectra of the H 2 -tagged, cryogenically cooled X ⁻ ∙HOCl (X = Cl, Br and I) ion-molecule complexes and analyze the resulting band patterns with electronic structure calculations and an anharmonic theoretical treatment of nuclear motions on extended potential energy surfaces. The complexes are formed by "ligand exchange" reac...

Recent studies have shown that pyruvic acid can produce higher-molecular-weight compounds upon irradiation in the aqueous phase. These compounds can contribute to the formation of secondary organic aerosols. There have been several previous studies on the effect of ionic strength on the photochemistry of pyruvic acid, however; few of them investiga...

While new particle formation events have been observed worldwide, our fundamental understanding of the precursors remains uncertain. It has been previously shown that small alkylamines and ammonia (NH3) are key actors in sub-3 nm particle formation through reactions with acids such as sulfuric acid (H2SO4) and methanesulfonic acid (CH3S(O)(O)OH, MS...

The photochemistry of carbonyl compounds is of considerable atmospheric importance, but the mechanisms and dynamics are often unknown. Here, we explore these topics for a system with adjacent keto and enol chromophoric groups. The photochemistry in the S1 and S2 states of the most stable tautomer of 1,2-cyclohexanedione, is studied theoretically us...

We introduce a new approach for analysing changes in electronic structure in the course of ab initio molecular dynamics simulations. The analysis is based on the time autocorrelation function of the many-body electronic wave-function. The approach facilitates the interpretation of dynamical events that may not be easily revealed by consideration of...

Atmospheric particles influence visibility, health and climate but the mechanisms of their formation from initial clusters and their growth to detectable particles remain largely unknown. Previous studies show that reactions of methanesulfonic acid (MSA) with ammonia and amines form particles, a process which is enhanced by water. We report here re...

Several multistep strategies were developed to ensure single methylation of amines on solid support. These strategies rely on the introduction of the o-NBS protecting/activating group as a key step. We found that the state-of-the-art strategies fail for the methylation of several primary amine motifs, largely due to inefficient sulfonylation. Here...

Experimental part, synthetic procedures, solid-phase synthesis protocols, HPLC chromatograms, mass spectrometry analysis.

Correction for 'New particle formation and growth from methanesulfonic acid, trimethylamine and water' by Haihan Chen et al., Phys. Chem. Chem. Phys., 2015, 17, 13699-13709.

Photochemical reactions of carbonyl molecules such as aldehydes, ketones, carboxylic acids and other species are among the largest and most important families of light-induced organic processes. The dynamical mechanisms of these processes are not well understood for relatively large molecules, and for carbonylic molecules in a solvent, or in an agg...

Significance Sulfur dioxide (SO 2 ) via its oxidation to sulfuric acid is a major source of airborne particles, which impact visibility, health, and climate. Sources of SO 2 include the combustion of sulfur-containing fossil fuels and the oxidation of organosulfur compounds (OSCs) such as dimethyl sulfide. We show that as fossil fuel combustion is...

New particle formation from gaseous precursors as a significant source of aerosol needs to be better understood to accurately predict the impacts on visibility, climate change and human health. While ternary nucleation of sulfuric acid, ammonia (NH3) and water is recognized as a significant driver for new particle formation, increasing evidence sug...

New particle formation from gas-to-particle conversion represents a dominant source of atmospheric particles and affects radiative forcing, climate and human health. The species involved in new particle formation and the underlying mechanisms remain uncertain. Although sulfuric acid is commonly recognized as driving new particle formation, increasi...

Molar absorption coefficients were measured for select alkyl nitrates and β-hydroxyalkyl nitrates in methanol. The presence of the β-hydroxyl group has a relatively minor effect on the absorption spectrum in the vicinity of the weak n → π* transition, which is responsible for photolysis of organic nitrates in the atmosphere. For both alkyl nitrates...

Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative exam...

Aerosol particles are ubiquitous in the atmosphere and have been shown to impact the Earth’s climate, reduce visibility, and adversely affect human health. Modeling the evolution of aerosol systems requires an understanding of the species and mechanisms involved in particle growth, including the complex interactions between particle- and gas-phase...

Proton-bound rare-gas dimer (RgHRg)(+), in which Rg represents a rare-gas atom, serves as a prototypical system for proton solvation by inert-gas atoms. Until now, only centrosymmetric species with both Rg = Ar, Kr, or Xe have been identified with infrared spectra. We employed electron bombardment during deposition of a mixture of Xe (or Kr) in p-H...

The formation of Criegee Intermediates by ozonolysis of different species containing C=N and C=P bonds is studied computationally. Electronic structure calculations are carried out for the energetics of ozonolysis, and the lifetime of the Criegee Intermediate formed is computed by transition state theory. All calculations are carried out for format...

The 3D structure of protein ions in the gas phase is presently not obtainable from experiment in atomic detail. Here we use a theoretical approach to determine the 3D structure of ubiquitin +13 (UBQ +13) in the absence of solvent. Global minimization of the UBQ +13 force field within the recently developed DEEPSAM algorithm yields a nearly linear o...

The interaction of water, 1,4 dioxane, and gaseous nitrogen dioxide, has been studied as a function of distance measured through the liquid-vapour interface by Raman spectroscopy with a narrow (<0.1 mm) laser beam directed parallel to the interface. The Raman spectra show that water is present at the surface of a dioxane-water mixture when gaseous...

High-level quantum chemical calculations reported here predict the existence and remarkable stability, of chemically-bound xenon atoms in fibrous silica. The results may support the suggestion of Sanloup and coworkers that chemically-bound xenon and silica account for the problem of "missing xenon" (by a factor of 20!) from the atmospheres of Earth...

We study the environmental effect on molecules embedded in noble-gas (Ng) matrices. The experimental data on HXeCl and HKrCl in Ng matrices is enriched. As a result, the H-Xe stretching bands of HXeCl are now known in four Ng matrices (Ne, Ar, Kr, and Xe), and HKrCl is now known in Ar and Kr matrices. The order of the H-Xe stretching frequencies of...

The reaction of (NO(+))(NO3(-)) with water is modelled in ONONO2·(H2O)4 clusters. Molecular Dynamics simulations using second-order Møller-Plesset perturbation (MP2) theory support the feasibility of the reaction of a charge-separated species to produce HONO and nitric acid.

The isomerization and decomposition dynamics of the simplest Criegee intermediate CH2 OO have been studied by classical trajectory simulations using the multireference ab initio MR-PT2 potential on the fly. A new, accelerated algorithm for dynamics with MR-PT2 was used. For an initial temperature of 300 K, starting from the transition state from CH...

Direct aqueous photolysis of cis-pinonic acid (PA; 2-(3-acetyl-2,2-dimethylcyclobutyl)acetic acid; CAS 473-72-3) by 280-400 nm radiation was investigated. The photolysis resulted in Norrish type II isomerization of PA leading to 3-isopropenyl-6-oxoheptanoic acid (CAS 4436-82-2), also known as limononic acid, as the major product, confirmed by H1 an...

The acidification of surfaces in the natural and built environments is important to atmospheric science because the process can enhance chemistry at surfaces and increase the release of highly reactive products into the gas phase. We present the results of an ab initio molecular dynamics study using density functional theory of HCl ionic dissociati...

Investigations of reactions pathways between a proton and cellobiose (CB), a glucose disaccharide of importance, were carried in cis and trans CB by Ab Initio Molecular Dynamics (AIMD) simulations started from optimized configurations where the proton is initially placed near groups with affinity for it. Near and above 300 K, protonated CB (H+CB) u...

HNgY molecules are chemically-bound compounds of a noble-gas atom (Ng) with a hydrogen and with an electronegative group Y. There is considerable current interest in the stability of these species in different types of media. The kinetic stability of several compounds, HXeOH, HXeOXeH, HXeBr and HXeCCH, in water clusters is explored by ab initio cal...

This study introduces an improved hybrid MP2/MP4 ab initio potential for vibrational spectroscopy calculations which is very accurate, yet without high computational demands. The method uses harmonic vibrational calculations with the MP4(SDQ) potential to construct an improved MP2 potential by coordinate scaling. This improved MP2 potential is used...

The vibrational spectroscopy of C-H stretches in organic molecules is of considerable importance for the characterization of these systems and for exploration of their properties. These stretches are strongly anharmonic, and thus methods including anharmonicity have to be used. The Vibrational Self-Consistent Field (VSCF) is applied to the followin...

The photochemistry of aldehydes in the gas phase has been the topic of extensive studies over the years. However, for all but the smallest aldehydes the dynamics of the processes is largely unknown, and key issues of the mechanisms are open. In this paper, the photochemistry of pentanal is studied by dynamics simulation using a semiempirical MRCI c...

Ammonia is the most abundant reduced nitrogen species in the atmosphere and an important precursor in the industrial-scale production of nitric acid. A coated-wall flow tube coupled to a chemiluminescence NOx analyzer was used to study the kinetics of NH3 uptake and NOx formation from photochemistry initiated on irradiated (λ > 290 nm) TiO2 surface...

Five small cyclic peptides and four implicit water models, were selected for this study. DEEPSAM, a structure prediction algorithm built upon TINKER, was used. Structures predicted using implicit water models were compared with experimental data, and with predictions calculated in the gas phase. The existence of very accurate X-ray crystallographic...

The interaction of NO(2) with water surfaces in the troposphere is of major interest in atmospheric chemistry. We examined an initial step in this process, the uptake of NO(2) by water through the use of molecular dynamics simulations. An NO(2)-H(2)O intermolecular potential was obtained by fitting to high-level ab initio calculations. We determine...

Chlorine atoms are highly reactive free radicals known to catalyze ozone depletion in the stratosphere and organic oxidation in the troposphere. They are readily produced photolytically upon irradiation of some stable Cl containing species, for instance, nitrosyl chloride, ClNO. We predict the formation of ClNO using ab initio molecular dynamics (A...

Equilibrium structures for a proton on β-d-galactose and transition states for proton hopping are computed. Also, Ab Initio Molecular Dynamics (AIMD) simulations are carried out. All calculations used B3LYP potentials with dispersion. At 40 K, proton hopping between sites is of near microsecond timescale. At 300 K, the proton migrates across the su...

Isomerization and ionization of N2O4 on model ice and silica surfaces, hypothesized as key steps in atmospheric HONO formation, were studied using B3LYP and MP2 methods. The models employed are (H2O)20 for ice and Si8O16H12 for silica. It is found that dangling surface –OH bonds play a key role in the isomerization to generate the ‘active’, asymmet...

The interaction of OH(-) with the sugar β-D-galactose is studied computationally, with Ab Initio Molecular Dynamics (AIMD) as the prime tool. The main findings are: (1) the OH(-) abstracts a proton from the sugar in a barrier-less process, yielding H(2)O and a Deprotonated beta-d-Galactose anion, (Dep-beta-D-G)(-). (2) This reaction can be reversed...

Noble-gas hydrides, generally prepared in noble-gas matrices, have fascinating chemical bonding and properties. However, very little is known on the kinetic stability of these compounds, and how it can be affected by different molecular environments and conditions. In this Letter, recent computational and experimental results bearing on this topic...

‘Bridging’ protons provide a common structural motif in biological assemblies such as proton wires and proton-bound dimers. Here we present a ‘proof-of-principle’ computational and vibrational spectroscopic investigation of an ‘intra-molecular proton-bound dimer,’ O-methyl α-D-galactopyranoside (αMeGal-H+), generated in the gas phase through photo-...

Peroxides are ubiquitous in the atmosphere and their photochemistry at ice surfaces is important. Here the primary steps following photoexcitation of methyl hydroperoxide (MHP) on ice particles are investigated using the MNDO method that describes semiempirically multiple electronic states and treats non-adiabatic dynamical transitions between them...

Ab initio vibrational self-consistent field (VSCF) calculations are used to predict the vibrational spectra of an extended series of monosaccharide·D(2)O complexes, including glucose, galactose, mannose, xylose, and fucose in their α and β anomeric forms, and compared with recently published experimental data for their (phenyl-tagged) complexes. An...

We present an exploration of proton transfer dynamics in a monosaccharide, based upon ab initio molecular dynamic (AIMD) simulations, conducted "on-the-fly", in β-d-galactose-H(+) (βGal-H(+)) and its singly hydrated complex, βGal-H(+)-H(2)O. Prior structural calculations identify O6 as the preferred protonation site for O-methyl α-d-galactopyranosi...

Solvation of β-cellobiose isomers, cis and trans, in increasingly larger water clusters, is examined here by means of ab initio dynamics. A previously suggested hydration motif, based on a cluster with 2 waters, provides a stable nucleation center for growth of the larger cluster. Key results: (a) the cis form is energetically favored throughout th...

Methyl peroxide (CH(3)OOH) is commonly found in atmospheric waters and ices in significant concentrations. It is the simplest organic peroxide and an important precursor to hydroxyl radical. Many studies have examined the photochemical behavior of gaseous CH(3)OOH; however, the photochemistry of liquid and frozen water solutions is poorly understoo...

Structure optimization, ab initio molecular dynamics (AIMD) simulation of transitions between structures, vibrational self-consistent field (VSCF) calculations of vibrational spectra and infrared ion dip (IRID) experiments have been used to explore the potential energy landscape of isomeric xylose·H2O (and D2O). The VSCF predictions are in close co...

Noble-gas hydrides such as HXeCCH are prepared in cryogenic noble-gas matrices where they are stable. Molecular dynamics simulations reported here predict that HXeCCH is chemically stable in clusters of acetylene, and that stability prevails for temperatures of at least 150 K, at which the clusters are liquid-like. The HXeCCH(C(2)H(2))(n) clusters...

Fourier-transform infrared and Raman scattering spectra of solid cellobiose are measured. The monitored spectra are compared to vibrational spectra of isolated cellobiose, computed by the vibrational self-consistent field (VSCF) method and from classical molecular dynamics (MD) simulations. Partial agreement is found between the measured and calcul...

First-principles anharmonic calculations are carried out for the IR and Raman spectra of the CH stretching bands in butane. The calculations use the Vibrational Self-Consistent Field (VSCF) algorithm. The results are compared with gas-state experiments. Very good agreement between the computed and experimental results is found. Theory is successful...

Proton transfer and dissociation processes following excitation of the OH or NH stretching modes of the proton-bound complex GlyLysH(+) are studied by classical trajectories. "On the fly" simulations with the PM3 semiempirical electronic structure method for the potential surface are used. Initial conditions are sampled to correspond to the v=1 exc...

A new algorithm is presented for finding the global minimum, and other low-lying minima, of a potential energy surface (PES) of biological molecules. The algorithm synergetically combines three well-known global optimization methods: the diffusion equation method (DEM), which involves smoothing the PES; a simulated annealing (SA) algorithm; and evo...

First-principles anharmonic vibrational calculations are carried out for the Raman spectrum of the C-H stretching bands in dodecane, and for the C-D bands in the deuterated molecule. The calculations use the Vibrational Self-Consistent Field (VSCF) algorithm. The results are compared with liquid-state experiments, after smoothing the isolated-molec...

The conformation and structural dynamics of cellobiose, one of the fundamental building blocks in nature, its C4' epimer, lactose, and their microhydrated complexes, isolated in the gas phase, have been explored through a combination of experiment and theory. Their structures at low temperature have been determined through double resonance, IR-UV v...

The anharmonic vibrational spectra of α-D-glucose, β-D-glucose, and sucrose are computed by the vibrational self-consistent field (VSCF) method, using potential energy surfaces from electronic structure theory, for the lowest energy conformers that correspond to the gas phase and to the crystalline phase, respectively. The results are compared with...

It is found that HRnCCH and HRnOH are metastable, chemically bound compounds of radon. These molecules are studied by multi-reference ab initio methods. Equilibrium geometry, NBO partial charges and bond orders, harmonic frequencies, are calculated. Intrinsic life-times are obtained by calculating the dissociation barriers and related partition fun...

Vibrational energy flow and conformational transitions following excitation of the OH stretching mode of the most stable conformer of glycine are studied by classical trajectories. "On the fly" simulations with the PM3 semiempirical electronic structure method for the potential surface are used. Initial conditions are selected to correspond to the...

The separable VSCF approximation and the VSCF-PT2 method are extensively used for anharmonic vibrational spectroscopy calculations of large molecules. VSCF-PT2 uses second-order perturbation theory to correct the VSCF level, and is thus more accurate. It is shown by test calculations for a series of amino acids and peptides that the mean deviation...

Simulations show that photodissociation of methyl hydroperoxide, CH3OOH, on water clusters produces a surprisingly wide range of products on a subpicosecond time scale, pointing to the possibility of complex photodegradation pathways for organic peroxides on aerosols and water droplets. Dynamics are computed at several excitation energies at 50 K u...

Molecular dynamics (MD) simulations are carried out for the complex of glucose with KNO(3) and for complexes of the type glucose-KNO(3)-(H(2)O)(n), for n < or = 11. Structure and dynamic properties of the systems are explored. The MD simulations are carried out using primarily the DL_POLY/OPLS force field, and global and local minimum energy struct...

High level ab initio calculations of clusters comprised of water, HCl, and ON-ONO(2) are used to study nitrosyl chloride (ClNO) formation in gas phase water clusters, which are also mimics for thin water films present at environmental interfaces. Two pathways are considered, direct formation from the reaction of gaseous HCl with ON-ONO(2) and an in...

Several complementary experimental and theoretical methodologies were used to explore water uptake on sodium chloride (NaCl) particles containing varying amounts of sodium dodecyl sulfate (SDS) to elucidate the interaction of water with well-defined, environmentally relevant surfaces. Experiments probed the hygroscopic growth of mixed SDS/NaCl nano...

The kinetic stability of the HXeOH and HXeOXeH molecules, chemically bound compounds made of Xe atoms and water, is studied by multi-reference ab initio methods. The decomposition paths, the transition states and the rates of dissociation as a function of temperature, are calculated. HXeOH and HXeOXeH are found to be protected by an energy barriers...

IR spectra of xenon hydrides (HXeCCH, HXeCC, and HXeH) obtained from different xenon isotopes ((129)Xe and (136)Xe) exhibit a small but detectable and reproducible isotopic shift in the absorptions assigned to H-Xe stretching (by 0.17-0.38 cm(-1)). To our knowledge, it is the first direct experimental evidence for the H-Xe bond in HXeY type compoun...

Structural properties of large NO(3)(-).(H(2)O)(n) (n = 15-500) clusters are studied by Monte Carlo simulations using effective fragment potentials (EFPs) and by classical molecular dynamics simulations using a polarizable empirical force field. The simulation results are analyzed with a focus on the description of hydrogen bonding and solvation in...

Gaseous HCl generated from a variety of sources is ubiquitous in both outdoor and indoor air. Oxides of nitrogen (NO(y)) are also globally distributed, because NO formed in combustion processes is oxidized to NO(2), HNO(3), N(2)O(5) and a variety of other nitrogen oxides during transport. Deposition of HCl and NO(y) onto surfaces is commonly regard...

Ionization of N(2)O(4) in and on thin water films on surfaces is believed to be a key step in the hydrolysis of NO(2) which generates HONO, a significant precursor to the OH free radical in the lower atmosphere. Molecular dynamics simulations using "on the fly" high-level MP2 potentials are carried out for ONONO(2) x (H(2)O)(n) clusters, n < or = 8...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electron spectroscopy for chemical analysis (ESCA) is a powerful tool for the quantitative analysis of the composition and the chemical environment of molecular systems. Due to the lack of compatibility of liquids and vacuum, liquid-phase ESCA is much less well established. The chemical shift in the static ESCA approach is a particularly powerful o...

Calculations were performed to determine the structures, energetics, and spectroscopy of the atmospherically relevant complexes (HNO(3)).(NO(2)), (HNO(3)).(N(2)O(4)), (NO(3)(-)).(NO(2)), and (NO(3)(-)).(N(2)O(4)). The binding energies indicate that three of the four complexes are quite stable, with the most stable (NO(3)(-)).(N(2)O(4)) possessing b...

Electrospray ionization transfers thermally labile biomolecules, such as proteins, from solution into the gas phase, where they can be studied by mass spectrometry. Covalent bonds are generally preserved during and after the phase transition, but it is less clear to what extent noncovalent interactions are affected by the new gaseous environment. H...

Raman spectra of HNO(3).NO(2) have been detected on liquid and solid surfaces in the presence of concentrated HNO(3) and NO(2) gas. The Raman spectrum of HNO(3) solutions containing N(2)O(4) has been partly reinterpreted in terms of contributions from HNO(3).N(2)O(4) and N(2)O(4).NO(3)(-) complexes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Lieber etwas größer: Der Protonentransfer im elektronischen Grundzustand von (C6H5NH−)⋅(H2O)n wurde photoelektronenspektroskopisch untersucht. Bei n=3 wird ein Proton eines Wassermoleküls durch das deprotonierte Anilin unter Bildung von solvatisiertem OH− abgespalten (siehe Bild). Diese Beobachtungen werden durch Ab-initio-Rechnungen gestützt, die...

The kinetic stability of the HXeCCH molecule, a chemically bound compound made of Xe and acetylene was studied by multi-reference ab-initio methods. The decomposition paths, transition states and the rates of dissociation as a function of temperature, for the dominant dissociation reactions were calculated. The HXeCCH molecule is found to be protec...

Evidence from cross section data indicates that ubiquitin +13 ions lose their secondary and tertiary structure in mass spectrometric experiments. These transitions from the folded state into the near linear final structure occur at the experimental temperatures on time scales that are far too long for conventional molecular dynamics simulations. In...

The vibrational spectrum of triacetone triperoxide (TATP) is studied by the correlation-corrected vibrational self-consistent field (CC-VSCF) method which incorporates anharmonic effects. Fundamental, overtone, and combination band frequencies are obtained by using a potential based on the PM3 method and yielding the same harmonic frequencies as DF...

A novel noble-gas compound, HXeOXeH, is identified using IR spectroscopy, and it seems to be the smallest known neutral molecule with two noble-gas atoms. HXeOXeH is prepared using, for example, UV photolysis of water in solid xenon and subsequent annealing at 40-45 K. The experimental observations are fully supported by extensive quantum chemical...

We have calculated frequencies and intensities of fundamental and overtone vibrational transitions in water and water dimer with use of different vibrational methods. We have compared results obtained with correlation-corrected vibrational self-consistent-field theory and vibrational second-order perturbation theory both using normal modes and fina...

The vibrational spectroscopy of a glycine molecule adsorbed on a silicon surface is studied computationally, using different clusters as models for the surface. Harmonic frequencies are computed using density functional theory (DFT) with the B3LYP functional. Anharmonic frequency calculations are carried out using vibrational self-consistent field...

A computational study is made of the number of important anharmonic mode-mode couplings in the context of vibrational calculations for di-, tri-, and tetrapeptides. The method employed is the correlation-corrected vibrational self-consistent field (CC-VSCF) algorithm, which includes correlation effects between different vibrational modes. It is fou...

Recombination events of a proton with NO3- at (H2O)8 clusters are studied by molecular dynamics, using "on-the-fly" reliable ab initio MP2 potentials. The main findings are: (1) the lifetime of the ions is less than 1.2 picoseconds; (2) the recombination step invariably involves H3O+, not H5O2+; and (3) an essentially unique transition-state struct...

Density functional theory (DFT) technique is the most commonly used approach when it comes to computation of vibrational spectra of molecular species. In this study, we compare anharmonic spectra of several organic molecules such as allene, propyne, glycine, and imidazole, computed from ab initio MP2 potentials and DFT potentials based on commonly...

The study of evaporation of water from biological macromolecules is important for the understanding of electrospray mass spectrometry experiments. In electrospray ionization (ESI), electrically charged nanoscale droplets are formed from solutions of, for example, proteins. Then evaporation of the solvent leads to dry protein ions that can be analyz...

The vibrational spectroscopy of (SO42−)∙(H2O)n is studied by theoretical calculations for n = 1–5, and the results are compared with experiments for n = 3–5. The calculations use both ab initio MP2 and DFT/B3LYP potential energy surfaces. Both harmonic and anharmonic calculations are reported, the latter with the CC-VSCF method. The main findings a...

The results of anharmonic frequency calculations on neutral imidazole (C3N2H4, Im), protonated imidazole (ImH+), and its complexes with water (ImH+)(H2O)n, are presented and compared to gas phase infrared photodissociation spectroscopy (IRPD) data. Anharmonic frequencies are obtained via ab initio vibrational self-consistent field (VSCF) calculatio...