High-resolution photoelectron imaging of cold ${\rm C}_{60}^ -$C60− anions and accurate determination of the electron affinity of C60

Self Cite

Electrospray ionization (ESI) has become an essential tool in chemical physics and physical chemistry for the production of novel molecular ions from solution samples for a variety of spectroscopic experiments. ESI was used to produce free multiply-charged anions (MCAs) for photoelectron spectroscopy (PES) in the late 1990 s, allowing many interesting properties of this class of exotic species to be investigated. Free MCAs are characterized by strong intramolecular Coulomb repulsions, which create a repulsive Coulomb barrier (RCB) for electron emission. The RCB endows many fascinating properties to MCAs, giving rise to meta-stable anions with negative electron binding energies. Recent development in the PES of MCAs includes photoelectron imaging to examine the influence of the RCB on the electron emission dynamics, pump-probe experiments to examine electron tunneling through the RCB, and isomer-specific experiments by coupling PES with ion mobility for biological MCAs. The development of a cryogenically cooled Paul trap has led to much better resolved PE spectra for MCAs by creating vibrationally cold anions from the room temperature ESI source. Recent advances in coupling the cryogenic Paul trap with PE imaging have allowed high-resolution PE spectra to be obtained for singly charged anions produced by ESI. In particular, the observation of dipole-bound excited states has made it possible to conduct vibrational autodetachment spectroscopy and resonant PES, which yield much richer vibrational spectroscopic information for dipolar free radicals than traditional PES.

Section: High-resolution Photoelectron Imaging and Spectroscopy Omentioning

confidence: 99%

Section: High-resolution Photoelectron Imaging and Spectroscopy Omentioning

confidence: 99%

Section: B Vibrational State-selective Resonant Two-photon High-resomentioning

confidence: 99%

See 1 more Smart Citation

Perspective: Electrospray photoelectron spectroscopy: From multiply-charged anions to ultracold anions

Wang

2015

Self Cite

Section: High-resolution Photoelectron Imaging and Spectroscopy Omentioning

confidence: 99%

A multi-agent quantum Monte Carlo model for charge transport: Application to organic field-effect transistors

Bauer

Jäger

Jordan

et al. 2015

We have developed a multi-agent quantum Monte Carlo model to describe the spatial dynamics of multiple majority charge carriers during conduction of electric current in the channel of organic field-effect transistors. The charge carriers are treated by a neglect of diatomic differential overlap Hamiltonian using a lattice of hydrogen-like basis functions. The local ionization energy and local electron affinity defined previously map the bulk structure of the transistor channel to external potentials for the simulations of electron- and hole-conduction, respectively. The model is designed without a specific charge-transport mechanism like hopping- or band-transport in mind and does not arbitrarily localize charge. An electrode model allows dynamic injection and depletion of charge carriers according to source-drain voltage. The field-effect is modeled by using the source-gate voltage in a Metropolis-like acceptance criterion. Although the current cannot be calculated because the simulations have no time axis, using the number of Monte Carlo moves as pseudo-time gives results that resemble experimental I/V curves.

“…The experiments reported in the current work were all performed by operating the ion trap at 4.4 K to achieve the best cooling. 50 The velocity-map imaging apparatus was calibrated with the PE images of Au − at several photon energies. The kinetic energy (KE) resolution achieved was 3.8 cm −1 for 55 cm −1 electrons and about 1.5% (∆KE/KE) for KE above 1 eV.…”

mentioning

confidence: 99%

Communication: Observation of dipole-bound state and high-resolution photoelectron imaging of cold acetate anions

Huang

Zhu

Wang

2015

Self Cite

We report the observation of a dipole-bound state and a high-resolution photoelectron imaging study of cryogenically cooled acetate anions (CH3COO−). Both high-resolution non-resonant and resonant photoelectron spectra via the dipole-bound state of CH3COO− are obtained. The binding energy of the dipole-bound state relative to the detachment threshold is determined to be 53 ± 8 cm−1. The electron affinity of the CH3COO neutral radical is measured accurately as 26 236 ± 8 cm−1 (3.2528 ± 0.0010 eV) using high-resolution photoelectron imaging. This accurate electron affinity is validated by observation of autodetachment from two vibrational levels of the dipole-bound state of CH3COO−. Excitation spectra to the dipole-bound states yield rotational profiles, allowing the rotational temperature of the trapped CH3COO− anions to be evaluated.