Extensive Electron-Nuclear Angular Momentum Exchange in Vibrational Autoionization of np and nf Rydberg States of NO (original) (raw)
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Optical-optical double resonance photoionization spectroscopy of nf Rydberg states of nitric oxide
The Journal of Chemical Physics, 2004
The spectra of vibrationally excited n f Rydberg states of nitric oxide were recorded by monitoring the photoion current produced using two-photon double resonance excitation via the NO A 2 ⌺ ϩ state followed by photoexcitation of the Rydberg state that undergoes autoionization. The optical transition intensities from NO A state to n f Rydberg states were calculated, and the results agree closely with experiment. These results combined with circular dichroism measurements allow us to assign rotational quantum numbers to the n f Rydberg states even in a spectrum of relatively low resolution. We report the positions of these n f (,N,N c) Rydberg levels converging to the NO X 1 ⌺ ϩ ϩ ϭ1 and 2 ionization limits where N is the total angular momentum excluding electron and nuclear spin and N c represents the rotational quantum number of the ion core. Our two-color optical-optical double resonance measurements cover the range of N from 15 to 28, N c from 14 to 29, and the principal quantum number n from 9 to 21. The electrostatic interaction between the Rydberg electron and the ion core is used to account for the rotational fine structure and a corresponding model is used to fit the energy levels to obtain the quadrupole moment and polarizability of the NO ϩ core. Comparison with a multichannel quantum defect theory fit to the same data confirms that the model we use for the electrostatic interaction between the n f Rydberg electron and the ion core of NO well describes the rotational fine structure.
Physical Review Letters, 2000
Rotationally resolved photoelectron angular distributions from vibrational autoionization of the NO 14s (n 1, N 20, N 1 R 20) level are measured by photoelectron spectroscopy, and they are analyzed using a theoretical model based on first-order coupling between the Rydberg level and the ionization continuum. The analysis reveals that l-changing collisions and l-changing collisions between the molecularion core and the outgoing electron are comparable in magnitude and account for 40% of the partial waves produced in the ionization continuum.
Faraday Discuss., 2016
An autoionizing resonance in molecular N2 is excited by an ultrashort XUV pulse and probed by a subsequent weak IR pulse, which ionizes the contributing Rydberg states. Time- and angular-resolved photoelectron spectra recorded with a velocity map imaging spectrometer reveal two electronic contributions with different angular distributions. One of them has an exponential decay rate of 20 ± 5 fs, while the other one is shorter than 10 fs. This observation is interpreted as a manifestation of interference stabilization involving the two overlapping discrete Rydberg states. A formalism of interference stabilization for molecular ionization is developed and applied to describe the autoionizing resonance. The results of calculations suggest, that the effect of the interference stabilization is facilitated by rotationally-induced couplings of electronic states with different symmetry.
Faraday Discussions, 2016
An autoionizing resonance in molecular N 2 is excited by an ultrashort XUV pulse and probed by a subsequent weak IR pulse, which ionizes the contributing Rydberg states. Time-and angularresolved photoelectron spectra recorded with a velocity map imaging spectrometer reveal two electronic contributions with different angular distributions. One of them has an exponential decay rate of 20 ± 5 fs, while the other one is shorter than 10 fs. This observation is interpreted as a manifestation of interference stabilization involving the two overlapping discrete Rydberg states. A formalism of interference stabilization for molecular ionization is developed and applied to describe the autoionizing resonance. The results of calculations reveal, that the effect of the interference stabilization is facilitated by rotationally-induced couplings of electronic states with different symmetry.
Autoionization widths of the NO Rydberg-valence state complex in the 11-12 eV region
The photoion excitation spectra of 14NO and 15NO have been studied in the 105-112 nm excitation region using high-order harmonic laser spectroscopy. Utilizing the small bandwidth offered by this technique, the natural widths of prominent lines in this region have been measured. These lines originate from interactions between high-lying Rydberg levels converging to the NO + electronic ground state and a 'new' NO valence state situated close to the latter state. The present measurements show broad resonances corresponding to a decay time of 20-50 fs. This supports the interpretation that the decay takes place via rapid electronic autoionization.
The Journal of Chemical Physics, 1991
Time-of-flight photoelectron spectroscopy has been used to record energy-resolved photoelectron angular distributions (PADS) following (1 + 1') resonance-enhanced multiphoton ionization (REMPI) of NO via the ui = l,N, = 22 rovibrational level of the A 28 + state. The PADS corresponding to single rotational states of the resulting molecular ion show a strong dependence on the change in ion core rotation AN(-N +-Ni) and also on the angle between the linear polarization vectors of the two light beams. Broken reflection symmetry [I(19,$) #I(-0,#) ] is observed when the polarization vectors of the two light beams form an angle of 54.P. A fit to the PADS provides a complete description of this molecular photoionization, namely, the magnitudes and phases of the radial dipole matrix elements that connect the intermediate state to the ]lil) photoelectron partial waves (Refs. 1 and 2). This information is then used to predict unobserved quantities, such as ion angular momentum alignment and the full three-dimensional form of the PADS.
The Journal of Chemical Physics, 1992
The photoionization process NO A 2~+ (v=O, N=22)-.NO+ X I~+ (v+=O, N+) +eis stu~ied with sufficient photoelectron energy resolution that the photoelectron angular distributions (PADs) associated with individual rotational levels N+ of the ion are determined. By. ionizing with left and right circularly polarized light and observing the change in the ro-tatIOnally resolved PADs, we can deduce all dynamical information, including the signs of the relative phase shifts of the photoelectron partial waves. This information constitutes the first complete description of the photoionization of a molecule. We discuss the consistency of our dynamical parameters with the Rydberg series of NO. We present a general formalism for (1 + 1') resonance-enhanced multiphoton ionization (REMPI) PADs for rotationally res~lve? i~n states using linearly po.larized light for excitation and elliptically polarized light for IOnIZatIOn. Based on the dynamIcal parameters determined from our fit, we use this formalism to predict the total system state, i.e., three-dimensional PADs and polarization of ion rotational levels following photoionization.
High-resolution zero-kinetic-energy photoelectron spectroscopy of nitric oxide
Physical review, 1987
Rotationally selective photoionization dynamics for the transition (NO+)X'Z+(v+ O, N+) (NO)A2Z+(v =0,1V&,J& Nz+-, ') is studied by high-resolution zero-kinetic-energy photoelectron spectroscopy (ZEKE-PES). Two-photon, two-color photoionization via the NO A state in a skimmed supersonic jet is employed in the experiments. The observed angular momentum transfer ion molecule is found to depend strongly on the initial quantum number N&. The ioniza'tion potential is determined to be 74719.0 0.5 cm
Chemical Physics Letters, 1995
Na, Rydberg states have been observed for 10 < n < 119 and 0 <J Q 9 using high resolution all-optical triple resonance spectroscopy and an ultrasensitive ionization detector. This represents the first example of high resolution triply resonant photoionization with cw lasers in any molecule. An improved ionization potential of Na, was estimated by extrapolation to be IP = 39478.75 f 0.04 cm-', corresponding to an improved molecular ion dissociation energy D, = 7973.83 + 0.12 cm-'. Four series, np 'ZT, np 'II,, nf 'xi and nf 'H,, were found and rovibrational interactions, 1 uncoupling, stroboscopic effects and Fano autoionization profiles were observed in the spectra.
Near-Threshold, Vibrationally-Resolved Photoionization of Molecular Nitrogen
Bulletin of the American Physical Society, 2015
Submitted for the DAMOP16 Meeting of The American Physical Society Near-Threshold, Vibrationally-Resolved Photoionization of Molecular Nitrogen GAETAN VANGYSEGHEM, THOMAS GORCZYCA, Western Michigan University, CONNOR BALLANCE, Queen’s University Belfast — Photoionization of molecular nitrogen (N2) is investigated near the first ionization threshold using an R-matrix, multi-channel quantum defect theory (MQDT) approach. Building on an existing fixed-nuclei R-matrix photoionization model [M. Tashiro, J. Chem. Phys. 132, 134306, (2010)], which, in turn, is built on the UKRmol suite of codes, photoionization cross sections, as well as scattering and dipole matrices, are computed in the Born-Oppenheimer approximation. By varying the internuclear separation, potential energy curves have been constructed for the N2 and N + 2 states and compared to quantum chemistry calculations. Using these fixed-nuclei potential energy curves, and corresponding vibronic eigenenergies and eigenfunctions, a...