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By employing the two-color infrared (IR)-vacuum ultraviolet (VUV) laser photoionization (PI) schemes, we have determined the C[Single_Bond]H stretching frequencies ν[sub 12]=3097.7 cm[sup -1] for trichloroethene (CHCl==CCl[sub 2]) and ν[sub 12][sup +]=3066 cm[sup -1] for CHCl==CCl[sub 2][sup +]. On the basis of the IR-VUV-pulsed field ionization-photoelectron (PFI-PE) measurement, the ratio of the state-to-state PI cross section for CHCl==CCl[sub 2][sup +](ν[sub 12][sup +]=1)←CHCl==CCl[sub 2](ν[sub 12]=1) to that for the formation of the ground state ion from the ground state neutral is determined to be 0.24. The VUV-PI efficiency (PIE) spectrum for CHCl==CCl[sub 2] and IR-VUV-PIE spectrum for CHCl==CCl[sub 2](ν[sub 12]=1) show that the state-to-state PI cross section for the formation of CHCl==CCl[sub 2][sup +] in the ground state from CHCl==CCl[sub 2](ν[sub 12]=1) is ≈0.006 that from CHCl==CCl[sub 2] in its ground state. As expected, the IR-VUV-PIE onset for CHCl==CCl[sub 2](ν[sub 12]=1) exhibits less hot-band tailing than the VUV-PIE onset for supersonically cooled CHCl==CCl[sub 2]. After taking into account the ν[sub 12] frequency, the ionization energy values for CHCl==CCl[sub 2] determined based on the IR-VUV-PIE and VUV-PFI-PE measurements are found to be in excellent agreement. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Describes the high-resolution energy-selected kinetic energy release measurement for the photoionization process SF(sub 6)+hv...SF( sub 5+)+F+e. Thermochemical threshold for the process; Calculated heats of formation at 0 K for SF(sub 5+) and SF(sub 5); Design and detailed performance of the chemical dynamics beamline.

Using two-colour visible (Vis)–ultraviolet (UV) photoionisation and pulsed field ionisation–photoelectron (PFI–PE) methods, we have obtained cleanly rotationally resolved photoelectron spectra for ZrO+(X2Δ3/2,5/2; v+= 0, 1, and 2). The rotation assignment of these state-to-state Vis–UV–PFI–PE spectra has allowed the unambiguous determination of the ground state term symmetry for ZrO+(X) to be2Δ3/2, and the adiabatic ionisation energy of90Zr16O, IE(90Zr16O) = 54,948.3(8) cm−1[6.81272(10) eV]. The symmetry of the ionic ZrO+(X2Δ3/2) ground state determined here disagrees with that reported in previous experiments. The rotational and vibrational constants determined in this experiment for the ionic90Zr16O+(X2Δ3/2) ground state are:Be+= 0.4343(8) cm−1and αe+= 0.0019(5) cm−1, and ωe+= 991.2(8) cm−1and ωe+xe+= 3.5(8) cm−1; and those for the ionic90Zr16O+(X2Δ5/2) excited spin-orbit state are:Be+= 0.4357(6) cm−1and αe+= 0.0022(4) cm−1, and ωe+= 991.9(8) cm−1and ωe+xe+= 3.6(8) cm−1, respectively. Based on the latterBe+value, the equilibrium bond distances are determined to bere+= 1.691(2) Å for90Zr16O+(X2Δ3/2) andre+= 1.688(1) Å for90Zr16O+(X2Δ5/2). The IE(ZrO) along with the spectroscopic constants obtained here are valuable for benchmarking theab initioquantum chemical calculations for energetic and structural predictions of ZrO/ZrO+. [ABSTRACT FROM AUTHOR]

Abstract: Recent developments of two-color infrared (IR)-vacuum ultraviolet (VUV) and VUV-IR photoionization and photoelectron detection schemes for spectroscopic studies are described. By preparing molecules in selected rovibrational states by IR excitation prior to VUV-photoionization, state-selected and state-to-state photoionization cross sections can be obtained by IR-VUV-photoionization efficiency (IR-VUV-PIE) and IR-VUV-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) measurements, respectively. Rotationally resolved autoionizing Rydberg states converging to excited ionic states, which cannot be observed by single-photon VUV-PIE measurements, can be examined by the IR-VUV-PIE scheme. By monitoring the photoion and the PFI-PE intensities at a fixed VUV energy as a function of IR frequency, the respective IR photoion and IR absorption spectra of the corresponding neutral molecule can be measured. Two-color VUV-IR photo-induced Rydberg ionization (PIRI) experiment, in which high-n Rydberg states are prepared by VUV-photoexcitation followed by IR-induced autoionization, has also been demonstrated. Since the IR-VUV-PIE, IR-VUV-PFI-PE, and VUV-IR-PIRI methods do not require the existence of a bound intermediate electronic state in the UV and are generally applicable to all molecules, the development of these two-color photoionization and photoelectron schemes is expected to significantly enhance the scope of VUV spectroscopy and chemistry. [Copyright &y& Elsevier]

Develops a sensitive and applicable scheme for performing pulsed field ionization photoelectron (PFI-PE)-photoion coincidence spectroscopy using two-bunch and multibunch synchrotron radiation at the Advanced Light Source. Provision of an ion internal state selection limited only by the PFI-PE measurement; Determination of kinetic energy releases.

Focuses on high resolution threshold and pulsed field ionization photoelectron spectroscopy using multi-bunch synchrotron radiation. Resolution for threshold photoelectron measurements; Characteristics of the monochromatized vacuum ultraviolet beam at the chemical dynamics beamline; Photoionization-photoelectron apparatus.

We have demonstrated that the time-of-flight (TOF) selection method for pulsed field ionization (PFI) photoelectron detection [Jarvis et al., Rev. Sci. Instrum. 70, 2615 (1999)] can also be applied for the detection of PFI-photoions (PFI-PIs) using the two-bunch synchrotron radiation at the Advanced Light Source. By employing the supersonic beam technique to lower the translational temperature of the sample gas, we show that background prompt ions formed in direct and spontaneous autoionization processes arrive at the ion detector in a pattern similar to that of the vacuum ultraviolet light bunches. The PFI-PIs formed at dark gaps can be designed to arrive at the detector in between adjacent prompt ion peaks, enabling the gating of the PFI-PI signal with only minor contamination from background prompt ions. This experiment has revealed important considerations for the design of a general TOF selection scheme for PFI-PI detection using synchrotron radiation. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]