By collision-energy/electron-energy-resolved 2D Penning ionization electron spectroscopy as well as by theoretical calculations of the collisional ionization dynamics, the outer shape of molecular orbitals for ionization to X(Σ) and A(Π) states of CO was sensitively probed, and the anisotropy of the interaction between He*(2S) and CO was determined. Ionization to the B(Σ) state of CO was assign...

Field ionization energy spectra of toluene, cycloheptatriene and phenolare reported. Details of the spectra are correlated with molecular proper-ties. The implications of the observation for analytical work are discussed. INTRODUCTIONField Ionization has proven to be a useful tool in the mass spectrometricstudy of organic molecules. This paper presents data which suggest tec...

An Analytical Band Monte Carlo model was used to investigate the temperature dependence of impact ionization in InAs. The model produced an excellent agreement with experimental data for both avalanche gain and excess noise factors at all temperatures modeled. The gain exhibits a positive temperature dependence whilst the excess noise shows a very weak negative dependence. These dependencies we...

Total chemi-ionization cross-sections have been measured over the 15 to 1 500 eV energy interval for collisions of He 2 1S and 2 3S metastable atoms with Ne, H2, N2, O2 and CO, using a slow ion measurement technique. With molecular targets these measurements have shown a strong energy dependence for the total ionization cross-section without dissociation. In the case of dissociative ionization ...

the present study describes the fragmentation under electron ionization (ei) of gas phase serine and threonine amino acids. ab initio methods were performed to calculate the fragmentation paths and interpret the mass spectra. the six lowest energy conformers of l-serine, l-threonine and l-allo-threonine were obtained with b3lyp, g3mp2 and mp2 methods. the adiabatic and vertical ionization energ...

Singleand double-ionization processes in C6+ collisions with the He atom at an incident energy of 100 MeV/amu are studied by direct solution of the time-dependent Schrödinger equation. A time-dependent close-coupling method based on an expansion of a one-electron three-dimensional wave function in the field of He+ is used to calculate single-ionization cross sections. A time-dependent close-cou...

The intrinsic ionization energy of a base in DNA plays a critical role in determining the energies at which damage mechanisms may emerge. Here, a two-photon resonance-enhanced ionization scheme is presented that utilizes the (1)ππ* transition, localized on the DNA base, to elucidate the base-specific ionization in a deprotonated nucleotide. In contrast to previous reports, the scheme is insensi...

Time-dependent close-coupling, R-matrix double pseudo-states and distorted-wave methods are used to calculate the electron-impact double ionization cross section for the 1s22s2 ground state of the Be atom. At 1.5 times the double ionization threshold energy, the first two non-perturbative methods predict a cross section of approximately 1.0 × 10−18 cm2 for the direct double ionization of the 2s...