Selective field ionization of high Rydberg states: Application to zero-kinetic-energy photoelectron spectroscopy

Abstract

Articles you may be interested inHigh-resolution pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopic study of the two lowest electronic states of the ozone cation O 3 + Assignment of the first five electronic states of Ar 2 + from the rotational fine structure of pulsed-field-ionization zero-kinetic-energy photoelectron spectra Sequences of pulsed electric fields have been designed and tested that enable a higher selectivity in the pulsed field ionization of high Rydberg states (nу100) than has so far been possible. The enhanced selectivity originates from the permutation of the parabolic quantum numbers n 1 and n 2 that is induced by a sufficiently rapid inversion of the electric field polarity during a pulse sequence. A reliable procedure, based on numerical simulations of the outcome of pulse field ionization sequences, has been developed to detect and control changes in the parabolic quantum numbers that can occur during a pulse sequence. The procedure can be used to assess under which conditions a clean permutation of the parabolic quantum numbers can be achieved. Unwanted randomization of m, n 1 and n 2 , which reduces the selectivity of the field ionization process, can be avoided by minimizing the time intervals during which the electric field in the pulse sequence is almost zero. The high selectivity reached in the pulsed field ionization of high Rydberg states has been used to record pulsed-field-ionization zero-kinetic-energy photoelectron spectra of argon and nitrogen at an unprecedented resolution of 0.06 cm Ϫ1 . This resolution opens new perspectives in photoelectron spectroscopy.

Photoelectron spectroscopic study of the E⊗e Jahn–Teller effect in the presence of a tunable spin–orbit interaction. I. Photoionization dynamics of methyl iodide and rotational fine structure of CH3I+ and CD3I+

“…These sequences consisted of a +166 mVcm −1 discrimination pulse of 1 μs duration followed by several field-ionization (and extraction) pulses of 200 ns duration and gradually decreasing strengths, as explained in Ref. 35. Steps of either −33, −17, or −8 mVcm −1 were used between adjacent pulses, starting with a pulse strength of −83 mVcm −1 .…”

“…34) and a photoelectron spectrometer described in Ref. 35. Tunable VUV radiation in the rangeν VUV = 76920-77000 cm −1 was generated by coherent four-wave difference-frequency mixing (ν VUV = 2ν 1 −ν 2 ) in a krypton gas cell using two pulse-amplified single-mode ring dye lasers.…”

The Rotational Structure of the Origin Band of the Pulsed-Field-Ionization, Zero-Kinetic-Energy Photoelectron Spectra of Propene-h6 and Propene-d6

“…Thanks to the continual improvement of its resolution resulting from the exploitation of electric field ionization sequences, 15,24,25 PFI-ZEKE photoelectron spectroscopy, initially applied to resolve the rotational structure in the photoelectron spectra of diatomic molecules, has rapidly been applied to obtain information on the rovibrational photoionization of more com- ethene, 31,32 and allene. 33 The present results on propene illustrate the possibility of partially resolving the rotational structure in single-photon photoelectron spectra of structurally more complex molecules.…”

“…The supersonic beam was skimmed and subsequently intersected the VUV laser beam at right angles in the photoionization region. 14 To achieve high-resolution in the photoelectron spectra, a multipulse electric-field sequence, 15,16 delayed by 2.0 µs relative to the time of photoexcitation and optimized to field ionize narrow slices of the pseudo-continuum of high-n Rydberg states below each ionization threshold, was applied.…”

High-resolution pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopic study of the two lowest electronic states of the ozone cation O3+

“…The first pulse with an amplitude of ϩ100 mV/cm and a duration of 500 ns was triggered 500 ns after the XUV laser pulse and served the purposes of removing spurious free electrons from the photoionization region and of narrowing down the range of Rydberg states which are field ionized by the subsequent pulse. 30 The second field pulse with an amplitude of Ϫ200 mV/cm was applied immediately after the first and the electrons released by this pulse were monitored by setting a suitable detection gate in the electron time-offlight spectrum. This pulse sequence enabled a resolution of ⌫ FWHM ϭ0.6 cm Ϫ1 in the PFI-ZEKE photoelectron spectra.…”