Yoshihiro Sumiyoshi

Infrared diode laser spectroscopy of the SiCl+ ion

The infrared diode laser spectrum of the SiCl+ ion generated in a discharge of SiCl4 mixed with He has been observed by the hollow cathode discharge modulation method. Sixteen and nine absorption lines for the Si35Cl+ and Si37Cl+ isotopic species, respectively, have been assigned to R and P branch transitions of the fundamental band. The spectroscopic constants derived from simultaneous analysis of both isotopic species are, for the Si35Cl+, ωe=678.310(69) cm−1, ωeχe=2.365(35) cm−1, Be=0.287034(19) cm−1, αe= 1.47866(82 ) × 10−3 cm−1 and De=2.171 (82) × 10−7 cm−1. The equilibrium bond length calculated from the rotational constant is re= 1.943890(69) A. The figures in parentheses are uncertainties corresponding to three standard deviations to be attached to the last digit.

Infrared diode laser spectroscopic detection of the propargyl radical produced in a supersonic jet expansion by UV laser photolysis

Abstract The propargyl radical (CH 2 CCH) was produced in a pulsed supersonic jet expansion by the 193 nm excimer laser photolysis of propargyl chloride, and detected by the method of time-resolved infrared diode laser spectroscopy. A rotational temperature of 16 ± 4 K was obtained in an experiment in which the τ Q 0 -branch lines of the v 6 band were observed. The characteristic behavior of the propargyl radical in a supersonic beam produced by circular and slit nozzles was discussed.

Time‐resolved infrared diode laser spectroscopy of the ν5 band of the cyanomethyl radical (H2CCN)

The infrared spectrum of the cyanomethyl radical (H2CCN) generated by the 193 nm excimer laser photolysis of chloroacetonitrile was observed by time‐resolved diode laser spectroscopy. About 50 lines, involving those split into doublet due to the spin–rotation interaction, were assigned to rovibrational transitions in the ν5 (CH2‐wagging) band of cyanomethyl. The molecular constants in the ν5 vibrational state were derived from the analysis of the observed wave numbers, resulting in the rotational constants, A=9.095 03(21) cm−1, (B+C)/2=0.335 363 4(41) cm−1, and (B−C)=0.011 503 6(71) cm−1, and the spin–rotation interaction constant eaa=−2.143(47)×10−2 cm−1, where the figures in parentheses are 2.5 standard deviations to be attached to the last digit, the constants in the ground state being fixed to the reported values from microwave spectroscopy. The band origin determined ν0=663.793 98(85) cm−1 is consistent with the value derived from the photo‐detachment spectroscopy of the H2CCN− anion. Large changes i...

Diode laser spectroscopy of SiH3 in the 4.5 μm region

Abstract The SiH3 radical, which plays an important role in plasma processes as well as in photo-excited processes, was investigated by high resolution infrared diode laser absorption spectroscopy. The radical was generated by the discharge of phenyl silane diluted with argon in a multi-pass absorption cell. The spectrum was recorded by the discharge modulation technique. About seventy spectral lines in the 4.5 μm region were unambiguously identified as belonging to the v3 (Si-H degenerated stretch) vibrational band of SiH3, and are available for application to monitoring by the infrared diode laser absorption spectroscopy (IRLAS) method.

A SEARCH FOR THE HOCO RADICAL IN THE MASSIVE STAR-FORMING REGION Sgr B2(M)

Rin Abe, Ayane Miyazaki, Takahiro Oyama, Mitsunori Araki, Shuro Takano, Nobuhiko Kuze, Yoshihiro Sumiyoshi, Koichi Tsukiyama, Yasuki Endo 1 Department of Chemistry, Tokyo University of Science, Japan 2 Department of Physics, College of Engineering, Nihon University, Japan 3 Department of Materials and Life Science, Sophia University, Japan 4 Division of Pure and Applied Science, Graduated School of Science and Technology, Gunma University, Japan 5 Department of Applied Chemistry, National Chiao Tung University, Taiwan