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High quantum efficiency enhancement is found for hybrid metal-insulator photocathodes consisting of thin films of CsI deposited on Cu(1 0 0), Ag(1 0 0), Au(1 1 1) and Au films irradiated by 266 nm laser pulses. Low work functions (near or below 2 eV) are observed following ultraviolet laser activation. Work functions are reduced by roughly 3 eV from that of clean metal surfaces. We discuss various mechanisms of quantum efficiency enhancement for alkali halide/metal photocathode systems and conclude that the large change in work function, due to Cs accumulation of Cs metal at the metal–alkali halide interface, is the dominant mechanism for quantum efficiency enhancement.

Using tools of density functional theory, we compute the Raman spectra of 1,3-propanedithiol (PDT) isolated in the gas phase, solvated in methanol, tethered either to the face or vertex of a tetrahedral Ag20 cluster, and bridging two Ag20 clusters. The derived molecular polarizability derivative tensors are used to simulate molecular orientation-dependent Raman scattering, achieved by rotating the polarizability tensors relative to vector components of the incident/scattered radiation fields. Our framework is weighed against SERS experiments which probe the optical response at a hotspot formed by an Ag surface coated with PDT and a single 60-nm Ag nanosphere.

We present a study of the lowest surface and bulk excitations of the well-studied potassium bromide (KBr) system using an embedded cluster method. The excited states of the embedded cluster are studied systematically using time-dependent density functional theory (TDDFT) and high-level equation-of-motion coupled cluster (EOMCC) methods. In particular, we have used EOMCC models with singles and doubles (EOMCCSD) and two approaches which account for the effect of triply excited configurations in non-iterative and iterative fashions. We compare and contrast the results between these theories as well as compare our results with experiment. The bulk–surface exciton shift is also calculated at the TDDFT level and compared with experiment.

Ultraviolet (UV) irradiation of amorphous and crystalline samples of solid acetyl chloride produces metastable HCl · ketene complexes in a 1:1 ratio following S 1 photoexcitation. The HCl · ketene complex is the only product observed following UV irradiation of either amorphous or crystalline samples. The condensed-phase reaction mechanism contrasts starkly with that of the gas phase mechanism that produces Cl and CH 3 CO radicals by prompt photolysis, followed by dissociation of internally excited CH 3 CO to form CO and CH 3 in a non-concerted process.

We have recently compared the (2 + 1) resonance enhanced multiphoton ionization spectra of neutral CO products desorbed from CaCO3 following pulsed UV excitation with those obtained from thermal (295 K) CO samples under similar low pressure and identical ionization conditions. As a result of this investigation, we have concluded that fitting the unresolved B-X (0-0) Q-band may lead to spurious temperature assignments with erroneous ‘hotter’ temperatures ΔT > 60 K assigned for product state distributions. Conversely, partially resolved Doppler-limited spectra are found to allow temperature assignments to within 10 K. This discrepancy may arise from line strength perturbation phenomena.

Kinetic and mechanistic studies of the gas-phase reactions between hydroxyl radicals and Cn alcohols (n⩾2) are described. Hydrogen-atom abstraction by OH from β-sites in alcohols produces HO-alkene intermediates that rapidly dissociate to OH + alkene at elevated temperatures. This reactive sequence consitutes a catalytic mechanism for the net transformation CnH2n+1OH→ H2O + CnH2n. The fraction of OH-alcohol reactivity that proceeds through this catalytic channel depends on the detailed molecular structure of the alcohol.