Newly available, powerful infrared laser sources enable the preparation of intense molecular beams quantum-state prepared and aligned molecules for gas/surface reaction dynamics experiments. We present a stereodynamics study chemisorption vibrationally excited methane on (100) surface nickel. Using linearly polarized excitation C-H stretch modes two isotopologues [CH4(nu3) CD3H(nu1)], we methane's angular momentum vibrational transition dipole moment in laboratory frame. An increase...

The competitive structural isomers of the Mo(2)O(y) (-)Mo(2)O(y) (y=2, 3, and 4) clusters are investigated using a combination anion photoelectron (PE) spectroscopy density functional theory calculations. PE spectrum calculations for MoO(3) (-)MoO(3) also presented to show level agreement be expected between spectra For (-) MoO(3), predict symmetric C(3v) structures, an adiabatic electron affinity 3.34 eV, which is above observed value 3.17(2) eV. However, there good calculated vibrational...

We present a stereodynamics study of the dissociative chemisorption vibrationally excited methane on (100), (110), and (111) planes nickel single crystal surface. Using linearly polarized infrared excitation antisymmetric C–H stretch normal mode vibration (ν3), we aligned angular momentum amplitude CH4(ν3) in laboratory frame measured alignment dependence state-resolved reactivity CH4 for ν3 = 1, J 0–3 quantum states over range incident translational energies. For all three surfaces studied,...

The determination of accurate size distributions and chemical composition volatile semivolatile ultrafine aerosol particles with sizes in the subnanometer to several tens nanometers range is a problem that plagues many studies research. We propose employ sodium-doping subsequent photoionization ultraviolet combined mass spectrometric detection solve this problem. Comparison "soft" EUV ionization demonstrates technique can determine some extent weakly bound largely destruction-free. also...

The fragmentation of methanol, water, dimethyl ether, and acetic acid clusters upon photoionization with a single vacuum ultraviolet (VUV) photon 10.1 eV, 13.3 or 17.5 eV energy is studied mass spectrometry. sodium-doping method used as an independent approximate measure the original cluster size distribution providing information on degree VUV ionization. experimental results show strong for (CH(3))(2)O CH(3)CO(2)H but minor H(2)O CH(3)OH clusters. pronounced decay explained by additional...

We report the first measurements of size-resolved photoelectron angular distributions for valence orbitals neutral water clusters with up to 20 molecules. A systematic decrease anisotropy is found 5-6 molecules, and most remarkably, convergence larger clusters. suggest latter be result a local short-range scattering potential that fully described by unit The cluster data detailed electron model are used predict slow photoelectrons in liquid water. Reasonable agreement experimental jet found.

Electron scattering cross sections are essential for the quantitative description of electron-induced processes in nanoconfined aqueous systems. Here we report on energy- and size-dependent water clusters with diameters between <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mo>∼</a:mo><a:mn>1.0</a:mn></a:mrow></a:math> 2.5 nm electron energies below <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mo>∼</b:mo><b:mn>32</b:mn></b:mrow></b:math> eV. The up to a...

We present a new experimental configuration for the study of size-dependent, angle-resolved photoelectron and photoion spectra weakly bound ultrafine aerosol particles targeted at particle sizes below ∼20 nm. It combines single photon ionization by tunable, table-top vacuum ultraviolet laser energies up to 18 eV with velocity map imaging detection independent size determination using Na-doping method. As an example, size-dependence valence spectrum dimethyl ether clusters aerosols is...

Angle-resolved photoelectron spectroscopy of the unpaired electron in sodium-doped water, methanol, ammonia, and dimethyl ether clusters is presented. The experimental observations complementary calculations are consistent with surface electrons for cluster size range studied. Evidence against internally solvated provided by angular distribution. trends ionization energies seem mainly determined degree hydrogen bonding solvent solvation ion core. onset water methanol do not level off at...

Low-energy electrons dissolved in liquid ammonia or aqueous media are powerful reducing agents that promote challenging reduction reactions but can also cause radiation damage to biological tissue. Knowledge of the underlying mechanistic processes remains incomplete, particularly with respect details and energetics electron transfer steps. In this work, we show how ultraviolet (UV) photoexcitation metal-ammonia clusters could be used generate tunable low-energy situ. Specifically, identified...

The reactions of Mo2Oy- suboxide clusters with both methane and ethane have been studied a combination mass spectrometry, anion photoelectron spectroscopy, density functional theory calculations. Reactions were carried out under "gentle" "violent" conditions. For methane, number products appeared the gentler source conditions that more logically attributed to dissociation upon reacting form MoCH2-, Mo(O)CH2-, HMo(O2)CH3-. With ethane, observed same gentle Mo(O)C2H2-, Mo(O)C2H4-, Mo(O2)C2H4-,...

Highly efficient preparation of molecules in a specific rovibrationally excited state for gas/surface reactivity measurements is achieved molecular beam using tunable infrared (IR) radiation from single mode continuous wave optical parametric oscillator (cw-OPO). We demonstrate that with appropriate focusing the IR radiation, crossing fixed frequency field experience Doppler tuning can be adjusted to achieve complete population inversion two-level system by rapid adiabatic passage (RAP). A...

The scattering of low kinetic energy electrons in large water clusters can be treated as an intermediate case between gas and condensed phase scattering.

We present a combined computational and threshold photoelectron photoion coincidence study of two isotopologues dimethyl ether, (DME − h6)n d6)n n = 1 2, in the 9–14 eV photon energy range. Multiple isomers neutral ether dimer were considered, all which may be present, exhibited varying C–H⋯O interactions. Results from electronic structure calculations predict that them undergo barrierless proton transfer upon photoionization to ground state cation. In fact, found relax same radical cation...

We propose angle-resolved photoelectron spectroscopy of aerosol particles as an alternative way to determine the electron mean free path low energy electrons in solid and liquid materials. The is obtained from fits simulated photoemission images experimental ones over a broad range different particle sizes. principal advantage approach twofold. First, studies can be performed for many materials, including liquids. Second, size-dependent anisotropy photoelectrons exploited addition changes...

Angle-resolved photoelectron spectroscopy opens a new avenue to probe the orbital character of solutes and solvents from nanoscale bulk.

We have investigated the solvation dynamics and genuine binding energy photoemission anisotropy of solvated electron in neutral water clusters with a combination time-resolved photoelectron velocity map imaging scattering simulations. The was probed UV probe pulse following above-band-gap excitation by an EUV pump pulse. is completed within about 2 ps. Only single band observed spectra, no indication for isomers distinct energies. Data analysis model reveals range 3.55–3.85 eV parameter...

Intriguing properties of photoemission from free, unsupported particles and droplets were predicted nearly 50 years ago, though experiments a technical challenge. The last few decades have seen surge research in the field, due to advances aerosol technology (generation, characterization, transfer into vacuum), development photoelectron imaging spectrometers, vacuum ultraviolet ultrafast light sources. Particles offer several advantages for studies. For example, spectra are dependent on...

The size dependence of the band position, bandwidth, and asymmetry parameter in valence photoelectron spectrum ammonia clusters ultrafine aerosol particles is investigated for aggregates with diameters up to ~7 nm. neutral are ionized by single photons at 13.318 eV from a tabletop vacuum ultraviolet laser. photoelectrons detected velocity map imaging spectrometer. distributions determined independently using Na-doping method. Up few tens molecules, first ionization energy (value maximum)...

This paper reports on a curiosity concerning magic numbers in neutral molecular clusters, namely related to the photoelectron anisotropy angle-resolved spectra. With combination of density functional calculations and experiment, we search for Na(H2O)n, Na(NH3)n, Na(CH3OH)n, Na(CH3OCH3)n clusters. In clusters high symmetry, highest occupied orbital can be delocalized over an extended region, forming symmetric charge distribution s character, which results pronounced angular distribution. We...

Abstract The famous nonmetal‐to‐metal transition in Na–ammonia solutions is investigated nanoscale solution droplets by photoelectron spectroscopy. In agreement with the bulk solutions, a strong indication for to metallic state found at an average metal concentration of 8.8±2.2 mole%. smallest entity phase be observed consists approximately 100–200 solvent molecules. quantification this critical size stepping stone toward deeper understanding these quantum–classical through direct modeling...

The high surface sensitivity and controlled charge state of submicron sized droplets is exploited to study low-energy electron transport through liquid interfaces using photoelectron imaging. Already a few charges on droplet are found modify the images significantly. For narrow escape barriers, comparison with an scattering model reveals pronounced quantum effects in form above-barrier reflections at kinetic energies below about 1 eV. observed susceptibility characteristics barrier might...

Single-shot velocity-map imaging is used to investigate ion emission mechanisms from under-dense NaCl nanoplasmas. Spatially inhomogeneous nanoplasma can be exploited retrieve size and orientation of free-flying aerosol particles.

The photoelectron spectra of WO3H(-) and WO2F(-) are presented analyzed in the context a series previous similar measurements on MO(y)(-) (M = Mo, W; y 0-3), MO4H(-) AlMOy(-) (y ≤ 4) complexes. electronic structures WO3H WO2F anion neutral complexes were investigated using B3LYP hybrid density functional method. WO3H(-), WO2F(-), previously measured AlWO3(-) show that corresponding neutrals, which transition metal centers all +5 oxidation state, have comparable electron affinities. In...