While existing ion mobility calculators are capable of feats as impressive as calculating collision cross sections (CCS) within a few per cent and within a very reasonable time, the simplifications assumed in their estimations precludes them from being more precise, potentially overreaching with respect to the interpretation of existing calculations. With ion mobility instrumentation progressively

We present an overview of experimental and theoretical investigations exploring the dynamical evolution of Rydberg-to-valence character in the electronically excited states of small polyatomic molecules. Time-resolved photoelectron imaging (TRPEI), in conjunction with high-level quantum chemistry calculations, permits detailed insight into the non-adiabatic processes operating in these systems and

We review the solvation of atomic, molecular or cluster ions in HNDs. After briefly discussing the properties of snowballs in bulk helium we consider experimental conditions for the efficient synthesis of charged, doped HNDs. We show that the cluster ions observed in conventional mass spectrometers originate from fission of highly charged HNDs. The ionization threshold of HNDs doped with alkalis reveals

The translation-rotation (TR) dynamics and spectroscopy of light molecules, e.g. H 2 , HD, HF, and H 2 O, inside nanoscale cavities such as those of fullerenes and in clathrate hydrates, is dominated by strong nuclear quantum effects (NQEs) to a degree that is without parallel among realistic molecular species. The NQEs include the large TR zero-point energy, quantisation of the translational centre-of-mass

In the context of tropospheric chemistry, Criegee intermediates denote carbonyl oxides with biradical/zwitterionic character (R1R2COO) that form during the ozonolysis of alkenes. First discovered almost 70 years ago, stabilised versions of Criegee intermediates formed via collisional removal of excess energy have interesting kinetic and mechanistic properties. The direct production and detection of

Dissociative chemisorption is one of the most significant steps in heterogeneous catalysis. The rate-limiting step for industrially important processes such as water gas-shift reaction and steam reforming of methane involves the dissociative chemisorption of water and methane, respectively. These reactions exhibit interesting mode-specificity and show a strong dependence on the surface temperature

Component density profiles at vapour–liquid interfaces of mixtures can exhibit a non-monotonic behaviour with a maximum that can be many times larger than the densities in the bulk phases. This is called enrichment and is usually only observed for low-boiling components. The enrichment is a nanoscopic property which can presently not be measured experimentally – in contrast to the classical Gibbs adsorption

Carbonyl oxides, R1R2COO, alternatively known as Criegee intermediates (CIs), are short-lived molecules produced from ozonolysis of alkenes. These ozonolysis reactions yield highly excited CIs, and most of them promptly decay with emission of the OH radical and other products. Some of the nascent CIs are stabilised by collisional relaxation with surrounding molecules, and react with atmospheric trace

The rapid development of computational hardware and software, as well as the advances in new theoretical methodologies have allowed quantum chemistry, in particular density functional theory, to become a fundamental tool in polymer science to predict, rationalise, develop and characterise polymeric materials. Quantum chemistry is able to provide insight into molecular properties for both electronic

Predicted almost forty years ago, the radiation from thermally populated excited electronic states has recently been recognised as an important cooling mechanism in free molecules and clusters. It has presently been observed from both inorganic clusters and carbon-based molecules in molecular beams and ion storage devices. Experiments have demonstrated that many of these systems radiate at rates approaching

We review our development on beyond Born–Oppenheimer (BBO) theory and its implementation on various models and realistic molecular processes as carried out over the last 15 years. The theoretical formulation leading to the BBO equations are thoroughly discussed with ab initio calculations. We have employed first principle based BBO theory not only to formulate single surface extended Born–Oppenheimer

Sunscreen formulations have been developed to provide an artificial protective barrier against the deleterious effects of overexposure to ultraviolet (UV) radiation in humans. Ultrafast pump-probe spectroscopy techniques have been an invaluable tool in recent years for determining the photochemistry of active ingredients in sunscreen formulations, predominantly UV filters, in both the gas- and solution-phases

Surface enhanced Raman scattering (SERS) substrates, composed of plasmonic nanostructures (PNSs) and photocatalyst semiconductors, have emerged as novel multifunctional nanomaterials for advanced engineering applications. These combinations improve the photocatalytic activity of such systems and extend their application as recyclable SERS substrates owing to their self-cleaning ability by photodegradation

Graphene, one of the most promising two-dimensional (2D) nanomaterials, has gained substantial attention in several areas of materials science. Due to its unique mechanical, electrical, optical, and thermal properties, graphene-based materials have triggered both numerous fundamental studies and technological applications. Out of several synthetic methods, chemical vapour deposition (CVD) has emerged

Formation and growth of atmospheric aerosols are governed by the Gibbs energy of complex formation ( ΔG⦵). A number of hydrogen bound bimolecular complexes in the gas phase at room temperature have been detected. In this review, we illustrate how ΔG⦵ can be determined by combining gas phase infrared spectroscopy and vibrational theory. The XH-stretching (where X is a heavy atom like O) fundamental

Quantum-mechanical methods of solving the polyatomic vibrational Schrödinger equation need higher quality zero-order approximations than ones originating from the harmonic oscillator (HO). Ladder operators built on the HO have a number of unique features simplifying both the operator perturbation theory and practical implementations of matrix-elements-based methods. Therefore, finding suitable ladder

Hydrogen is the most abundant element. It is also the most quantum, in the sense that quantum tunnelling, quantum delocalisation, and zero-point motion can be important. For practical reasons, most computer simulations of materials have not taken such effects into account, rather they have treated nuclei as classical particles. However, thanks to methodological developments over the last few decades

Photoactive proteins that efficiently and selectively transfer light energy into a physical response are ubiquitous in nature. The small molecule chromophores that lie at the heart of these processes often exist as closed-shell anions following deprotonation in proton-transfer reactions. This review highlights the important role that anion photoelectron spectroscopy, combined with computational chemistry

The Time Dependent Discrete Variable Representation (TDDVR) method was initiated by Adhikari and Billing considering time dependent Gauss-Hermite basis functions, where all the parameters were assumed to be time dependent. Adhikari et al. had reformulated the TDDVR approach considering the width parameter as time independent, whereas the equation of motion for time dependent parameters (center of wave

Over the last decade, the spectroscopy of cryogenically cold ions isolated in the gas phase has been developed as a new tool for structural elucidations of biological molecules. Cooling allows for vibrational resolution in UV and IR spectra of small to midsize peptides, enabling different multi-laser techniques of conformer-specific spectroscopy. In conjunction with quantum chemistry calculations,

Aqueous charge injection in forms of electrons, protons, lone pairs, ions, and molecular dipoles by solvation is ubiquitously important to our health and life. Pursuing fine-resolution detection and consistent insight into solvation dynamics and solute capabilities has become an increasingly active subject. This treatise shows that charge injection by solvation mediates the O:H–O bonding network and

An approximate variational method based in the use of distributed Gaussian functions (DGF) and bond-length coordinates has been applied to study the rotation–vibration spectra of different triatomic molecules. In addition, an approach which employs hyperspherical coordinates and a basis set of hyperspherical harmonics constitutes a valid benchmark to test its capabilities. This work describes the technical

Measuring viscosity and temperature on the microscale is a challening yet very important task, in materials sciences and in biology alike. In this perpsective we review and discuss fluorescent microviscosity sensors, termed ‘molecular rotors’, that offer a convenient way of measuring microscopic viscosity and sometimes may even be used to measure microscopic temperature in addition to viscosity. We

Atoms in highly excited Rydberg states possess physical characteristics quite unlike those associated with atoms in the ground or low-lying excited states. In particular, they are physically very large and are only very weakly bound. In consequence, collisions can lead to a wide variety of reaction processes many of which are unique to Rydberg species and have very large collision cross sections. In

An alternative to the transition state (TS) pathway, the roaming route, which bypasses the minimum energy path but produces the same molecular products, was recently found in photodissociation dynamics. This account describes signatures of roaming in photodissociation of the carbonyl compounds, specifically methyl formate and aliphatic aldehydes. Methyl formate was promoted to the excited state, followed

Instanton theory provides a simple description of a quantum tunnelling process in terms of an optimal tunnelling pathway. The theory is rigorously based on quantum mechanics principles and is derived from a semiclassical approximation to the path-integral formulation. In multidimensional systems, the optimal tunnelling pathway is generally different from the minimum-energy pathway and is seen to ‘cut

Small molecular species present in mitochondria as, e.g. quinones and oxygen, can capture cellular electrons thus behaving as electron carriers or reactive species, supporting the fundamental process of respiration, and providing protection from pathogens. When xenobiotics penetrate living cells, their delicate redox balance can be altered by capture of cellular electrons to form temporary negative

The review presents a critical analysis of the data obtained from vibrational spectroscopic studies on a narrow selection of weak hydrogen-bonded binary molecular complexes for measurements performed under isolated conditions, addressing the nature, properties, physical origins of the binding forces, and the role of such hydrogen bonds in dynamics of vibrational relaxations. In the recent history of

The development of switchable mechanically interlocked molecular architectures (MIMAs) is an active area of experimental and theoretical research because the environmental-responsiveness of these systems makes them desirable candidates for incorporation into molecular machines. Presented here is a review of the recent literature that reports theoretical and computational studies of these topologically

In this article we address the general approach for calculating dynamical dipole polarizabilities of small quantum systems, based on a sum-over-states formula involving in principle the entire energy spectrum of the system. We complement this method by a few-parameter model involving a limited number of effective transitions, allowing for a compact and accurate representation of both the isotropic

During the last decade, density function theory (DFT) in its static and dynamic time dependent forms, has emerged as a powerful tool to describe the structure and dynamics of doped liquid helium and droplets. In this review, we summarise the activity carried out in this field within the DFT framework since the publication of the previous review article on this subject [M. Barranco et al., J. Low Temp

A critical review of experimental studies and ab initio calculations of the low-lying ungerade excited and ground state interatomic potentials of Cd2 van der Waals dimer is presented. Consistency as well as discrepancies between experimental results and ab initio calculations are probed. In order to obtain better agreement with existing experimental data, fill in gaps in current knowledge and provide

More than two decades of inelastic X-ray scattering (IXS) studies on noble gases and alkali metals are reviewed to illustrate the advances they prompted in our understanding of the terahertz dynamics of simplest systems. The various literature results outline a remarkably coherent picture of common and distinctive behaviours of liquids and their crystalline counterparts. Furthermore, they draw a consistent

Over the last decade, ultrafast two-dimensional infrared (2D IR) spectroscopy has been greatly advanced in a variety of aspects and is becoming a more exciting vibrational tool for understanding the structures and dynamics of condensed-phase equilibrium and non-equilibrium molecular systems, as well as surface-immobilised monolayers or adsorbates. A number of novel multi-pulse experimental schemes

We review a selection of recent experimental and theoretical cross section results for electron scattering from a range of biofuels (methanol, ethanol), biomolecules (water, tetrahydrofuran, pyrimidine, tetrahydrofurfuryl alcohol and para-benzoquinone) and molecular fragments that are formed from the action of atmospheric-pressure plasmas on biomass (phenol, furfural). Where possible, the implications

This review is concerned with the formation of molecules in the interstellar medium (ISM), which is composed mainly of regions of gas and dust known as interstellar clouds, ranging in size from a few to 100’s of light years in extent. Upwards of 200 different molecules have been observed spectroscopically in these objects, with a significant fraction of them ‘large’ by astronomical standards; i.e.

The importance of how a protein reconfigures its structure to achieve its function has long been appreciated; yet, the progress in our fundamental understanding of protein dynamics does not seem to be commensurate with the rapid advances in experimental techniques and ever increasing computational prowess. In this review, we attempt to look at this issue based on quantitative characterisations that

It is now confirmed that the Zhu–Nakamura (ZN) theory of nonadiabatic transition is useful to investigate various nonadiabatic chemical dynamics. The theory, being one-dimensional, presents a whole set of analytical formulas that enables us to treat the dynamics efficiently. It is also quite significant that classically forbidden transitions can be dealt with analytically. The theory can be combined

This review discusses the recent developments in our understanding of the electron transfer and bond-forming reactions of small atomic and molecular dications in the gas-phase. A summary of the properties of isolated dications is presented, followed by a review of the major experimental techniques used to probe dicationic reactivity. Electron transfer reactions of dications with neutral species are

Water and its fragments are present on metal surfaces under all but the most extreme conditions, acting both as a reactive species and as a ligand in ways that have yet to be fully explored. This review focuses on experimental studies of the chemical species and hydrogen bonding structures that form in the first layer adsorbed on a metal surface. The development of non-invasive probes that avoid dissociating

Although the solid state is typically characterised by inherent periodicity, many interesting physical and chemical properties of solids arise from a variation in this, i.e. changes in the nature of the atom occupying a particular site in a crystal structure or variation in the position of an atom (or group of atoms) in different parts of a structure, or variation as a function of time. This lack of

Ultrafast X-ray crystallography of the photoactive yellow protein with femtosecond delays using an X-ray free electron laser has successfully probed the dynamics of an early Franck-Condon species. The femtosecond pump-probe application of protein crystallography represents a new experimental regime that provides an X-ray structural probe for coherent processes that were previously accessible primarily

(2016). Editorial Board. International Reviews in Physical Chemistry: Vol. 35, No. 4, pp. (ebi)-(ebi).

The well-known correlation between structure and functionality has motivated generations of scientists to intensively investigate the structural behaviour of peptide and protein systems, e.g. their folding, their aggregation reactions or the process of molecular recognition. A variety of environmental effects on peptide structures occur among them the influence of solvent molecules or aggregation partners;

The formation of elongated supra-molecular structures from protein building blocks generates functional intracellular filaments, but this process is also at the heart of many neurodegenerative conditions including Alzheimer’s and Parkinson’s diseases, where it occurs in an uncontrolled manner. When observed at appropriate concentration and time scales, the chemical kinetics of filamentous protein self-assembly

A new representation for chemical kinetics based on a sum over histories formulation is discussed. The description of the time-dependent chemistry of a reaction network is provided by chemical pathways defined at a molecular level. Using this methodology, the quantitative time evolution of the kinetics is described by enumerating the most important pathways followed by a chemical moiety such as a tagged

(2016). Cryogenic Ion Trap Vibrational Spectroscopy of Hydrogen-Bonded Clusters Relevant to Atmospheric Chemistry (International Reviews in Physical Chemistry, 2015, Vol. 34, No. 1, 1–34) International Reviews in Physical Chemistry: Vol. 35, No. 3, pp. 507-507.

With advances in ab initio theory, it is now possible to calculate electronic energies within chemical (<1 kcal/mol) accuracy. However, it is still challenging to represent faithfully a large number of ab initio points with a multidimensional analytical function over a large configuration space, which is needed for accurate dynamical studies. In this Review, we discuss our recent work on a new potential-fitting

The recently developed method of frequency-, angle-, and time-resolved photoelectron imaging (FAT-PI) applied to the study of the dynamics of resonances of open-shell anions is reviewed. The basic principles of the method and its experimental realisation are outlined. The dynamics of a number of radical quinone anions is then considered. Firstly, we show for para-benzoquinone how frequency- and angle-resolved

Recent developments in single and multireference electronic structure methods and the approaches suitable to generate ab initio data that may be employed in the construction of global molecular potential energy surfaces are reviewed. The most appropriate, robust, accurate and cost effective strategies are discussed in the context of various applications ranging from cold collisions and weakly interacting

Natural bond orbital (NBO) analysis is one of many available options for ‘translating’ computational solutions of Schrödinger’s wave equation into the familiar language of chemical bonding concepts. In this Review, we first address the title questions by describing characteristic features that distinguish NBO from alternative analysis methodologies (e.g. of QTAIM or EDA type) and answering criticisms

The unique physical and tunable optical properties of noble metal nanoparticles (NPs) provides the opportunity to develop new sensing platforms with enhanced capabilities in the specific detection of a variety of small molecules. While noble metal NPs are interesting as nanomaterials, future and practical applications as high-performance novel functional materials will require the use of these NPs

Collisions with electrons from several sources are common throughout planetary atmospheres. While in most circumstances direct electron impact is less significant than solar radiation, electron collisions have a major influence on the chemistry driven by both photon and particle impact. This review addresses electron collisions in atmospheres, with emphasis on cases where electron impact drives, enhances

The literature on the high-resolution spectroscopic investigation of molecular complexes containing small polyatomic species excited in their vibrational overtones is reviewed. They turn out to be complexes containing acetylene, ammonia and water, mainly excited in their 2CH, 2NH and 2OH vibrations, respectively. The majority of results published on these systems was obtained using an instrumental

Resonance-stabilised hydrocarbon radicals serve as reaction intermediates in flames, plasmas, atmospheres and interstellar space. Their stability is conferred by delocalisation of the radical electron through a conjugated -system. As such, they tend to have low-lying electronic states which engender a rich optical spectroscopy. Over the last sixty years, and intensively over the last decade, the spectra

The interaction between hydrogen donor and acceptor molecules, known well as hydrogen bonding, forms a ubiquitous network in the natural and synthesis world. The hydrogen bonding role has thus been the subject of intensive work in the past. In this article, we discuss and show how the new mechanisms have been established in terms of the hydrogen bonding changes by reviewing some of the combined experimental

This paper presents a review of the bubble column evaporator (BCE) and its many novel applications. The BCE process offers a continuously produced source of high air–water interface and consequently provides high overall heat and mass transfer coefficients. Although the bubbling process itself is both simple to use and apply, our understanding of the fundamental physical and chemical principles involved

Photoelectron spectroscopy (PES) in combination with computational chemistry has been used systematically over the past decade to elucidate the structures and chemical bonding of size-selected boron clusters. Small boron clusters have been found to be planar or quasi-planar, consisting of a monocyclic circumference with one or more interior atoms. The propensity for planarity has been found to be a

One of the most commonly employed methods to study doped helium clusters is the path integral Monte Carlo (PIMC) approach. In this review we present results of recent investigations on a series of both atomic and diatomic dopants attached to droplets formed with up to 40 He atoms. Besides the comparison with similar studies existing in the literature, this work also gives the possibility to analyse

The expected depletion of fossil fuel reserves and its serious environmental impact have emphasised the issue of sustainable development of the human society. Solar hydrogen by photocatalytic water splitting is a promising alternative to conventional fossil fuels, which is of great potential to relieve the energy and environmental issues and bring an energy revolution in a clean and sustainable manner