Author: James Edward PollardPublisher:
ISBN:
Category :
Languages : en
Pages : 338
Book Description
Photoelectron Spectroscopy of Supersonic Molecular Beams
Author: James Edward PollardPublisher:
ISBN:
Category :
Languages : en
Pages : 338
Book Description
Photoelectron Spectroscopy of Supersonic Molecular Beams
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new technique for performing high resolution molecular photoelectron spectroscopy is described, beginning with its conceptual development, through the construction of a prototypal apparatus, to the initial applications on a particularly favorable molecular system. The distinguishing features of this technique are: (1) the introduction of the sample in the form of a collimated supersonic molecular beam; and (2) the use of an electrostatic deflection energy analyzer which is carefully optimized in terms of sensitivity and resolution. This combination makes it possible to obtain photoelectron spectra at a new level of detail for many small molecules. Three experiments are described which rely on the capability to perform rotationally-resolved photoelectron spectroscopy on the hydrogen molecule and its isotopes. The first is a measurement of the ionic vibrational and rotational spectroscopic constants and the vibrationally-selected photoionization cross sections. The second is a determination of the photoelectron asymmetry parameter, .beta., for selected rotational transitions. The third is an investigation of the rotational relaxation in a free jet expansion, using photoelectron spectroscopy as a probe of the rotational state population distributions. In the closing chapter an assessment is made of the successes and limitations of the technique, and an indication is given of areas for further improvement in future spectrometers.
High Resolution Photoelectron Spectroscopy and Femtosecond Intramolecular Dynamics Using Supersonic Molecular Beams
Author: Baohua NiuHigh Temperature and High Resolution Uv Photoelectron Spectroscopy Using Supersonic Molecular Beams
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 15
Book Description
A high temperature molecular beam source with electron bombardment heating has been built for high resolution photoelectron spectroscopic studies of high temperature species and clusters. This source has the advantages of: producing an intense, continuous, seeded molecular beam, eliminating the interference of the heating mechanism from the photoelectron measurement. Coupling the source with our hemispherical electron energy analyzer, we can obtain very high resolution HeI[alpha] (584Å) photoelectron spectra of high temperature species. Vibrationally-resolved photoelectron spectra of PbSe, As2, As4, and ZnCl2 are shown to demonstrate the performance of the new source. 25 refs., 8 figs., 1 tab.
Photoelectron Photoion Molecular Beam Spectroscopy
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The use of supersonic molecular beams in photoionization mass spectroscopy and photoelectron spectroscopy to assist in the understanding of photoexcitation in the vacuum ultraviolet is described. Rotational relaxation and condensation due to supersonic expansion were shown to offer new possibilities for molecular photoionization studies. Molecular beam photoionization mass spectroscopy has been extended above 21 eV photon energy by the use of Stanford Synchrotron Radiation Laboratory (SSRL) facilities. Design considerations are discussed that have advanced the state-of-the-art in high resolution vuv photoelectron spectroscopy. To extend gas-phase studies to 160 eV photon energy, a windowless vuv-xuv beam line design is proposed.
High Resolution Photoelectron Spectroscopy and Femtosecond Intramolecular Dynamics Using Supersonic Molecular Beams
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 192
Book Description
High resolution He I[alpha] photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a soft'' mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.
Photogeneration and Characterization of Energetic Molecules in Supersonic Molecular Beams
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 15
Book Description
A variety of weakly bound and/or metastable molecules have been investigated in the environment of a pulsed supersonic molecular beam. Experiments were attempted with little success for the production of metastable oxygen ring systems. Other experiments focused on metal ion and metal neutral complexes with small molecules or rare gas atoms. Spectroscopic studies were successful for magnesium ion complexes with the rare gases and with carbon dioxide, water, and nitrogen. Aluminum atom van der Waals complexes were studied with high resolution photoelectron spectroscopy. These studies obtained a variety of new data on metal condensation energetics and the structure of the initial phases of condensation.
Photoelectron Spectrum of Allene Using a Supersonic Molecular Beam Source
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Observations pertaining to the photoelectron spectrum of the 2E ground electronic state of the allene ion which exhibits strong Jahn-Teller effects.
Photoelectron Spectroscopy of Molecular Beams
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
From chemical spectroscopy and photochemistry in the vacuum ultraviolet conference; Valmorin, Quebec, Canada (5 Aug 1973). The development of the field of photoelectron spectroscopy and the intensities and angular distributions from which one can infer transition probabilities and phase shifts are discussed. (JFP).
Author: Dennis James Trevor