Two-color photoionization spectroscopy of polyatomic molecules and cations: aniline, phenol and phenotole (original) (raw)
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Physical Chemistry Chemical Physics, 2011
The phenol + Á Á ÁAr 2 complex has been characterized in a supersonic jet by mass analyzed threshold ionization (MATI) spectroscopy via different intermediate intermolecular vibrational states of the first electronically excited state (S 1). From the spectra recorded via the S 1 0 0 origin and the S 1 b x intermolecular vibrational state, the ionization energy (IE) has been determined as 68 288 AE 5 cm À1 , displaying a red shift of 340 cm À1 from the IE of the phenol + monomer. Well-resolved, nearly harmonic vibrational progressions with a fundamental frequency of 10 cm À1 have been observed in the ion ground state (D 0) and assigned to the symmetric van der Waals (vdW) bending mode, b x , along the x axis containing the CO bond. MATI spectra recorded via the S 1 state involving other higher-lying intermolecular vibrational states (s 1 s , b 3 x , s 1 s b 1 x , s 1 s b 2 x) are characterized by unresolved broad structures.
Phys. Chem. Chem. Phys., 2011
The phenol + Á Á ÁAr 2 complex has been characterized in a supersonic jet by mass analyzed threshold ionization (MATI) spectroscopy via different intermediate intermolecular vibrational states of the first electronically excited state (S 1). From the spectra recorded via the S 1 0 0 origin and the S 1 b x intermolecular vibrational state, the ionization energy (IE) has been determined as 68 288 AE 5 cm À1 , displaying a red shift of 340 cm À1 from the IE of the phenol + monomer. Well-resolved, nearly harmonic vibrational progressions with a fundamental frequency of 10 cm À1 have been observed in the ion ground state (D 0) and assigned to the symmetric van der Waals (vdW) bending mode, b x , along the x axis containing the CO bond. MATI spectra recorded via the S 1 state involving other higher-lying intermolecular vibrational states (s 1 s , b 3 x , s 1 s b 1 x , s 1 s b 2 x) are characterized by unresolved broad structures.
Proceedings of the 69th International Symposium on Molecular Spectroscopy, 2014
Recent advances in high-resolution photoionization, photoelectron, and photodissociation studies based on single-photon vacuum ultraviolet (VUV) and two-color infrared (IR)-VUV, visible (Vis)-ultraviolet (UV), and VUV-VUV laser excitations are illustrated with selected examples. VUV laser photoionization coupled with velocity-map-imaging threshold photoelectron (VMI-TPE) detection can achieve comparable energy resolution but has higher-detection sensitivities than those observed in VUV laser pulsed field ionization photoelectron (PFI-PE) measurements. For molecules with known intermediate states, IR-VUV and Vis-UV excitation schemes are highly sensitive for rovibronically selected and resolved PFI-PE studies. The successful applications of the VUV-PFI-PE, VUV-VMI-TPE, and Vis-UV-PFI-PE methods to state-resolved and state-to-state photoelectron studies of transient radicals and transitional metal-containing molecules are highlighted. The most recently established VUV-VUV pump-probe time-slice VMI photoion method is shown to be promising for state-to-state photodissociation studies of small molecules relevant to planetary atmospheres and for the fundamental understanding of photodissociation dynamics.
The Journal of Physical Chemistry, 1995
The picosecond predissociation dynamics of vibronic levels of the B and e' Rydberg states of ammonia have been investigated in real time by (2 + 1') two-color pump-probe ionization in combination with photoelectron spectroscopy. The picosecond real-time results are in reasonable agreement with the results obtained from indirect methods using nanosecond excitation. These indirect methods include investigations of the peak intensities and the natural line widths of the rotational lines in the excitation spectra. The photoelectron spectra obtained for (2 + 1) ionization via the B state in NH3 and ND3 are interpreted and shown to allow for an accurate determination of hitherto unknown vibrational frequencies in the ground state of NH3' (ND3+). For the VI symmetric stretch a frequency of 0.404 f 0.007 eV (0.304 f 0.007 eV) is found, while the frequency of the v4 asymmetric bend vibration has been established as 0.197 f 0.007 eV (0.141 f 0.007 eV). The hydrogen atom fragment, which results from the predissociation of the B and e' Rydberg states, has been detected in a two-color pump-probe experiment using nanosecond excitation.
Journal of Photochemistry and Photobiology A: Chemistry, 2012
We applied the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibrationally resolved spectra of the selected isotopomers of o-chloroanisole in the electronically excited S 1 and cationic ground D 0 states. As supported by our theoretical calculations, only the trans form of o-chloroanisole involves in the two-photon photoexcitation and ionization processes. The band origins of the S 1 ← S 0 electronic transition and adiabatic ionization energies for the 35 Cl and 37 Cl isotopomers of o-chloroanisole are found to be the same within our detection limit, with the values of 35 745 ± 2 and 66 982 ± 5 cm −1 , respectively. The general spectral features of the two isotopomers are nearly identical and result from in-plane ring deformation and substituent-sensitive bending and stretching as well as the CH 3 torsional motions.
The photoionization and dissociation of molecules
1966
The photoionization and dissociation of molecules was studied using a combination of a vacuum monochromator and a mass spectrometer. The work was performed to obtain fundamental information about some simple molecules and their ions, and it was hoped that this method, would provide a good means for the determination of accurate ionization potentials. Photoionization efficiency curves of sixteen.atoms and molecules, namely: argon, krypton, xenon, oxygen, nitrogen, carbon monoxide, chlorine, hydrogen chloride, ammonia, water, methane, methane-d^, propylene, acetylene, methyl cyanide and methyl alcohol for the energy range from eight to twenty-one electron volts were obtained. Numerical values of ionization and appearance potentials were determined from the initial onset of the photoionization efficiency curves, and the ionization potentials are discussed and compared with those obtained by other investigators. The threshold ionization potentials of these molecules are in close agreement with the spectroscopic values and are superior to those obtained by the electron impact method. The shape of the photoionization efficiency curve near the threshold gives an indication as to the type of electron removed in the photoionization process, and the correct electronic configuration of the molecule can 1 some-timesbe deduced from the numerical values of the ionization potentials as demonstrated in the case of methyl cyanide. The dissociation of ammonia, methane, methane-d^, propylene, acetylene, methyl cyanide and methyl alcohol was studied, and the mechanisms for the dissociation processes were discussed. From the photoionization efficiency curves of the fragment ions, numberical values of bond dissociation energy, ionization potentials of radicals and zero-point difference for the isotopic ions are deduced. Autionization processes were observed in the study of krypton, xenon, oxygen, nitrogen, carbon monoxide, hydrogen chloride and acetylene. That the peaks observed in the photoionization efficiency curves of these species are indeed due to autoionization has been confirmed by comparison with corresponding peaks in the optical absorption spectra. The vibrational. frequencies of hydrogen chloride and acetylene in the excited states could be deduced from the energy separation between two adjacent autoionization peaks.
Chemical Physics Letters, 1982
... [ 111 J. Murak.inu, K Kaya and II. Ilo, J. Chem. Phys. 72 (1980)3363. [12) DM. Rider, J Durant, SL Anderson, D. Proch and R N. Zaic, to be published. (131 M C. While, R A. Roscntn-re, G Gabor, ED Poijakolf, G. Thornton, SH Soullworlh and DA Shirlcy, Rev. ...
Chemical Physics, 1996
The heterotrimer phenol-water-Ar, a complex containing two different types of intermolecular bonds-a van der Waals bond and a hydrogen bond-has been studied in a supersonic jet with various spectroscopic techniques. The two-photon, two-color (1 + 1') resonance-enhanced multiphoton ionization (REMPI) spectrum of the S, state shows striking differences compared to the spectrum of the corresponding complex without water. From the zero kinetic energy photoelectron (ZEKE) spectrum an accurate ionization energy and the frequencies of all three van der Waals vibrations of the ionic ground state have been obtained. Comparison of the ZEKE and REMPI spectra of phenol-water-Ar with the corresponding spectra of phenol-Ar and phenol-water indicates that the stronger hydrogen bond noticeably influences the weaker van der Waals bond, while vice versa the hydrogen bond is nearly not affected by the additional van der Waals bond. Sharp steps in the photoionization efficiency (PIE) spectra of phenol-water-Ar and the fragment complex phenol-water provide an upper limit for the dissociation energy of the van der Waals bond in the ionic state, and from this value upper limits for the binding energies in both neutral states (S,, S,) have been derived. For comparison, REMPI and PIE spectra have also been recorded for phenol-water-Ne. Finally, the first mass-analyzed threshold ionization spectrum of a hydrogen-bonded complex, namely phenol-water, has been recorded in order to demonstrate that this technique can also be utilized for such type of complexes.
Physical chemistry chemical physics : PCCP, 2015
The structure of the phenol-argon cluster (PhOH-Ar) in high-n Rydberg states is investigated by the newly developed technique of mass analyzed threshold ionization detected infrared (MATI-IR) spectroscopy. This method selectively measures IR spectra of molecular clusters in very high-n Rydberg states (n > 100) utilized in zero kinetic energy (ZEKE) photoelectron and MATI spectroscopy, whose ionic cores are essentially the same as the corresponding bare cation. The MATI-IR spectrum exhibits only the free OH stretching vibration (ν) when the π-bound cluster of the neutral ground electronic state (S0) is resonantly excited via the S1 origin to Rydberg states converging to its adiabatic ionization energy level, IE0(π). When Rydberg states converging to vibrationally excited levels of the local π-bound minimum are prepared, in addition to ν also the hydrogen-bonded OH stretching vibration (ν) of the H-bonded global minimum is observed in the MATI-IR spectra, even for vibrational excit...
Review of Scientific Instruments, 2003
A two-color, vacuum ultraviolet ͑VUV͒-infrared ͑IR͒, photoionization study using monochromatized undulator VUV synchrotron radiation and high-repetition rate IR optical parametric oscillator ͑OPO͒ laser source has been demonstrated at the Chemical Dynamics Beamline of the Advanced Light Source. The OPO setup, optical alignment, and ion detection arrangement are described. The VUV-IR ionization spectrum of Ar has been recorded in the energy region between the ionization thresholds for Ar ϩ (2 P 3/2) and Ar ϩ (2 P 1/2) to illustrate the feasibility and efficacy of this scheme as a general approach for high-resolution two-color photoionization studies. The autoionization resonances of the Ar(npЈ and n f Ј) Rydberg series are resolved up to the principal quantum number of nϭ57, showing that the optical resolution of 0.3 cm Ϫ1 ͑full width at half maximum͒ achieved in this two-color photoionization study is mostly limited by the bandwidth of the IR OPO laser and the Doppler width due to the random motion of the Ar sample.