Jürgen Vogt

Feshbach-resonances and dissociative electron attachment of H2O

Abstract In order to obtain a better understanding of the dissociative electron resonance capture processes of H 2 O we have remeasured the ionization efficie The relative intensities of these curves are strongly dependent on the ion focusing conditions; the observed maxima however (7.0 eV, 9.1 eV, 11.8 eV) a We interpret the resonances as due to Feshbach states associated with the three lowest Koopmans ions of H 2 O; this interpretation is supported by a

Geometry optimization in ab initio SCF calculations. VII. Proton affinities and ion structures calculated with floating orbital geometry optimization (FOGO)

Abstract The FOGO method is used to calculate absolute proton affinities of the molecules H2, HF, NH3, H2O, CH3OH, C2H5OH, H2O2, CH2O, CO, and CH2CO. Comparison with experimental values demonstrates that the geometrical and energetical data resulting from this type of ab initio calculation are of chemical accuracy. Predictive data for higher energy isomers, such as hydroxymethylene and ethynol are given as possible aid for the identification of these species.

Microwave and millimetre wave spectra of diazirine-d2: Rotational and hyperfine structure analysis and molecular structure

The rotational spectrum of diazirine-d2, , has been recorded in the ranges 8–40 and 100–400u2002GHz. The hyperfine structure of the measured rotational lines has been analyzed. The analysis required the treatment of two pairs of equivalent nuclei, which is discussed in detail. The deduced deuterium nuclear-quadrupole coupling constants areThe quadrupole coupling constants of the nitrogen nucleiare taken from the parent species, and the spin-rotation coupling constants areThe rotational and centrifugal distortion constants have been obtained for the ground vibrational state from the analysis of the unperturbed line positions. The complete rs structure of diazirine has been determined using the rotational constants of all available isotopomers of diazirine. The internuclear distances are rs(C—N)u2002=u2002148.13(24)u2002pm, rs(C—H)u2002=u2002108.03(29)u2002pm, and rs(N—N)u2002=u2002122.80(25)u2002pm, and the bond angles are and , with the HCH plane perpendicular to the NCN plane.

The Fourier transform and diode laser spectrum of the ν2 band of diazomethane

Abstract The infrared spectrum of the ν 2 band (NN stretching) of gaseous diazomethane at 2100 cm −1 has been measured by means of an interferometer and a tunable diode laser spectrometer. For the first time the rotational J and K a structure of this A-type parallel band has been resolved. Since the spectrum was found to be perturbed it was not possible to fit the upper state levels to an overall hamiltonian. Nine subbands have been analysed with the support of millimeter wave data for the ground vibrational state. Term values for the ν 2 = 1 vibrational state with K a up to 5 have been obtained and subband origins, effective rotational constants B and centrifugal distortion constants D and H were determined for each K a substate.

The rotational a-type spectrum of [13C]diazirine, H2CN2

The rotational spectrum of 13C isotopically enriched diazirine, H213C14N2, has been recorded in the region between 12 and 250u2002GHz. From an analysis of the nuclear hyperfine structure of the rotational transitions, quadrupole coupling and spin-rotational constants have been determined. Using Watsons A-reduced Hamiltonian, the rotational constants, the quartic and some sextic centrifugal distortion constants have been obtained for the ground vibrational state. The rotational constants obtained areThe nuclear quadrupole coupling constants and the spin-rotation constants arefor the two identical quadrupolc nitrogen nuclei. The accuracy of the constants obtained allows us to evaluate the line positions and hyperfine structure of any rotational transition in the microwave and millimetre wave region.

The rotational a-type sepctra of 15N-labeled diazirine, H2CN2

Abstract The rotational a -type spectra of isotopically enriched diazirine isotopomers, H 2 12 C 14 N 15 N and H 2 12 C 15 N 2 , have been recorded in the region between 8 and 300 GHZ; the latter isotopomer has been observed for the first time. Using Watsons A -reduced Hamiltonian, the rotational constants and the quartic and some sextic centrifugal distortion constants have been determined for the ground vibrational states.

Rovibrational analysis of the v3 band of diazomethane, H2CNN

Abstract The ν3 fundamental of diazomethane. which essentially corresponds to a symmetric methylene deformation has been reinvestigated at a resolution of 0.07 cm-1 . The J- and Ka-structures of this A-type band have been resolved and analysed for the first time. The rovibrational assignment is given and, using Watsons S-reduced Hamiltonian, the rotational and quartic centrifugal distortion constants could be determined for the first excited vibrational state of the symmetric methylene deformation.

The infrared spectrum of diazirine, H2C15N2 rovibrational analysis of the v3 fundamental

The mid-infrared spectrum of 15N-labeled diazirine has been recorded using a Fourier transform spectrometer at a resolution of 0.08 cm-1. The v3 fundamental at 1452.49 cm-1 which essentially corresponds to a symmetric methylene deformation has been analyzed in detail. The rovibrational assignment is given and, using Watson’s A-reduced Hamiltonian, the rotational and centrifugal distortion constants for the v3 = 1 level could be determined.

l-Type Doublet Transitions of the Rare Stable Isotopic Species of Hydrogen Cyanide, HCN

l-type doublet transitions for HCN molecules in the first excited bending state 0110 have been measured for the isotopic species H13C14N, H12C15N, H13C15N, D13C14N, D12C15N and D13C15N. The measurements improve and complete the set of available coupling constants of the vibrationrotation interaction in this bending mode. All known l-type coupling constants are collected and compared with those obtained from the l-type splitting of the rotational lines and those obtained from ab-initio calculation of the energy hypersurface.