Browsing by Author "Wu, Pei-Zhen"

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Direct IR Absorption Spectra of Propargyl Cation Isolated in Solid Argon
(2018-09-26)
Chin, Chih-Hao
;
Lin, Meng-Yeh
;
Huang, Tzu-Ping
;
Wu, Pei-Zhen
;
Wu, Yu-Jong
The direct infrared (IR) absorption spectra of propargyl cations were recorded. These cations were generated via the electron bombardment of a propyne/Ar matrix sample during matrix deposition. Secondary photolysis with selected ultraviolet (UV) light was used for grouping the observed bands of various products. The band assignment of the propargyl cation in solid Ar was performed according by referring to the previous infrared photodissociation (IRPD) and velocity-map imaging photoelectron (VMI-PE) data, and via theoretical predictions of the anharmonic vibrational wavenumbers, band intensities, and deuterium-substituted isotopic ratios. Almost all the IR active bands with an observable intensity were recorded and the nu(11) mode was reported for the first time.
Formation of Halogen-bearing Species. I. Irradiation of Methyl Fluorides in Carbon Monoxide Ice with VUV Light and Electrons
(2019-08-01)
Lin, Meng-Yeh
;
Huang, Tzu-Ping
;
Wu, Pei-Zhen
;
Chin, Chih-Hao
;
Wu, Yu-Jong
We studied the synthesis of fluorine-bearing species by the irradiation of CO ice containing a small proportion of CH3F at 10 K with vacuum ultraviolet (VUV) light and energetic electrons. Photolysis of the ice sample with VUV light with a wavelength of 121.6 nm produced mainly fragments of CH3F, whereas both carbon oxides and fragments of CH3F were generated by irradiation with broadband VUV light. In contrast, electron irradiation of a similar ice sample generated not only those products observed in the photolysis experiments, but also complex organic hydrocarbons and fluorinated (carbon) oxides. This observation of the distinctive effect of the formation of different products by different excitation sources provides an insight into the energetic processes occurring in interstellar icy dust grains.
Formation of Halogen-bearing Species. II. Irradiation of Chloromethane in Carbon Monoxide Ice with VUV Light and Electrons
(2020-01-01)
Lin, Meng-Yeh
;
Huang, Tzu-Ping
;
Wu, Pei-Zhen
;
Chin, Chih-Hao
;
Wu, Yu-Jong
The synthesis of chlorine-bearing species in CO ice was studied by the irradiation of CH3Cl:CO ice at 10 K with vacuum-ultraviolet (VUV) light and energetic electrons. In contrast to the photochemical behavior of CH3F:CO ice, photolysis of CH3Cl:CO ice with Ly alpha or broadband VUV light afforded various products. This discrepancy was attributed to the abundant absorption bands of CH3Cl in the VUV region, particularly in the Ly alpha region. The Cl-bearing species including Cl2O, ClCO, C3Cl2, C3HCl, and HOOCl were characterized by observing their IR features. In contrast, electron bombardment of ice mixtures produced various carbon oxides and primary products, such as CH2Cl and HCO. In addition, the mechanism of energetic processes in electron bombardment was discussed.
Infrared Spectra of the 1-Methylvinoxide Radical and Anion Isolated in Solid Argon
(2019-06-06)
Lin, Meng-Yeh
;
Huang, Tzu-Ping
;
Wu, Pei-Zhen
;
Chin, Chih-Hao
;
Wu, Yu-Jong
The 1-methylvinoxy radical (1-MVO) is an important intermediate in the combustion and tropospheric reaction of OH. However, the vibrational structures of this species and its anionic form, 1-methylvinoxide anion (1-MVO-), are not fully known. Thus, in this study, we obtained the infrared (IR) absorption spectra of 1-MVO and 1-MVO- trapped in a solid Ar matrix. 1-MVO- anions were produced by electron bombardment during matrix deposition of Ar containing a small amount of acetone. The anions were destroyed upon irradiation at 675, 365, and 160 nm, although the formation of 1-MVO was only observed upon irradiation at 675 nm. The assignment of the IR bands of 1-MVO- and 1-MVO was based on the expected chemistry upon photoexcitation and comparison of line wavenumbers, relative IR intensities, and D-isotopic shift ratios with those predicted at the B3LYP/aug-cc-pVTZ level of theory.