scholarly journals Multiphoton Ionization of Formaldehyde: Observation of 3py and 3pz Rydberg States

1987 ◽  
Vol 7 (1) ◽  
pp. 35-40 ◽  
Author(s):  
D. S. Bomse ◽  
S. Dougal
Keyword(s):  
Cross Sections ◽  
Vibrational Excitation ◽  
Multiphoton Ionization ◽  
Rydberg States ◽  
Resonant Absorption ◽  
Photon Excitation ◽  
Hot Band ◽  
Low Probability ◽  
Photon Ionization ◽  
Absorption Measurements

Multiphoton ionization (MPI) of CH2O and CD2O is reported for dye laser wavelengths between 445 and 470 nm. The ionization pathway starts with three-photon resonant absorption to 3py and 3pz Rydberg states. One or two additional photons are required, depending on wavelength, to reach threshold. MPI spectra agree well with VUV absorption measurements of the same Rydberg levels. MPI yields are small and photoacoustic measurements imply the initial three-photon excitation has low probability. Transitions at the four-photon ionization threshold show larger cross sections than the (overall) five-photon ionization bands but hot band transitions were not observed following selective vibrational excitation of ground state molecules.

scholarly journals Resonant excitation of molecules by low-energy electrons

2008 ◽  
Vol 6 (1) ◽  
pp. 41-55 ◽  
Author(s):  
Goran Poparic
Keyword(s):  
Cross Sections ◽  
Valence State ◽  
Vibrational Excitation ◽  
Rydberg States ◽  
Low Energy ◽  
Resonant Excitation ◽  
Excitation Spectra ◽  
Energy Excitation ◽  
The Cross ◽  
Near Threshold

Low-energy electron impact vibrational and electronic excitation cross sections of the CO, N2 and CO2 molecules are measured by use of a high resolution crossed-beams double trochoidal electron spectrometer. The spectrometer is designed to work in standard and time-of-flight regimes. The energy dependences of the resonant vibrational excitation of the first several vibrational levels of the N2, CO, and CO2 molecules, have been measured. Characteristic substructures in energy excitation spectra in the cases of N2 and CO have been obtained and discussed for some vibrational channels for the first time. The ratio of forward-to-backward scattered electrons from the 2? resonance in CO is found to be equal to 1, and thus the angular distribution of scattered electrons to be symmetric relative to 90?. This conclusion supports the fact that the contribution of the p? partial wave is dominant in the energy region of the 2? resonance in CO. The energy dependences of the near threshold resonant excitation of the valence and Rydberg states of the N2 and CO molecules have been measured. The cross sections of the near threshold resonant excitation of the C 3?u valence state, and the E 3?+ g and a'' 1?+ g Rydberg states of the N2 molecule have been measured. In the case of the CO molecule, the cross sections of the near threshold resonant excitation of the a 3? valence state, and the b 3?+ and B 1?+ Rydberg states have been measured. Resonant structures in excitation functions of all measured electronic states are observed and their locations are compared with resonances obtained in different decay channels.

Multiphoton ionization of H2+ in the perturbative regime

2010 ◽  
Vol 88 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Samira Barmaki ◽  
Stéphane Laulan
Keyword(s):  
Perturbation Theory ◽  
Cross Sections ◽  
Multiphoton Ionization ◽  
High Energy ◽  
High Energy Resolution ◽  
Resonance Structures ◽  
Internuclear Axis ◽  
Perturbative Regime ◽  
Photon Ionization ◽  
Ionization Processes

Multiphoton ionization of the H 2+ hydrogen molecular ion at fixed internuclear distance is investigated in the lowest order perturbation theory (LOPT). The parallel and perpendicular orientations between the polarization laser vector of the electric field and the H 2+ internuclear axis direction are considered. We calculate the generalized cross sections for the N = 2 to N = 6 photon ionization processes and we identify in each case the intermediate-state resonances. We show the efficiency of our method to describe resonance structures with high-energy resolution.

Cross sections for resonant vibrational excitation ofN2by electron impact

1981 ◽  
Vol 23 (3) ◽  
pp. 1089-1099 ◽  
Author(s):  
A. U. Hazi ◽  
T. N. Rescigno ◽  
M. Kurilla
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Vibrational Excitation

scholarly journals The Cross Section for the J = 0 → 2 Rotational Excitation of Hydrogen by Slow Electrons

1969 ◽  
Vol 22 (6) ◽  
pp. 715 ◽  
Author(s):  
RW Crompton ◽  
DK Gibson ◽  
AI McIntosh
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
The Cross ◽  
Excitation Processes ◽  
Slow Electrons ◽  
And Diffusion ◽  
Momentum Transfer Cross Section ◽  
Section Analysis

The results of electron drift and diffusion measurements in parahydrogen have been analysed to determine the cross sections for momentum transfer and for rotational and vibrational excitation. The limited number of possible excitation processes in parahydrogen and the wide separation of the thresholds for these processes make it possible to determine uniquely the J = 0 → 2 rotational cross section from threshold to 0.3 eV. In addition, the momentum transfer cross section has been determined for energies less than 2 eV and it is shown that, near threshold, a vibrational cross section compatible with the data must lie within relatively narrow limits. The problems of uniqueness and accuracy inherent in the swarm method of cross section analysis are discussed. The present results are compared with other recent theoretical and experimental determinations; the agreement with the most recent calculations of Henry and Lane is excellent.

Determination of absolute two-photon excitation cross sections by in situ second-order autocorrelation

1995 ◽  
Vol 20 (23) ◽  
pp. 2372 ◽  
Author(s):  
Chris Xu ◽  
Winfried Denk ◽  
Jeffrey Guild ◽  
Watt W. Webb
Keyword(s):  
Cross Sections ◽  
Second Order ◽  
Two Photon ◽  
Photon Excitation ◽  
Excitation Cross Sections ◽  
Two Photon Excitation
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