Infrared spectroscopic study of rovibrational states of perdeuterated methane (CD4) trapped in parahydrogen crystal

Abstract

Articles you may be interested inSurvey of the high resolution infrared spectrum of methane (12CH4 and 13CH4): Partial vibrational assignment extended towards 12 000 cm−1The triply degenerate stretching ( 3 ) and bending ( 4 ) modes of CD 4 in solid parahydrogen at cryogenic temperatures are studied by Fourier transform infrared spectroscopy to reveal crystal field split rovibrational structures. The observed spectra are analyzed by taking into account the crystal field potential which is constructed by the summation of the pairwise ͑dispersive͒ potential between the methane and the surrounding hydrogen molecules. By the least-squares fitting of that observed to a theoretical model the molecular constants of CD 4 as well as the potential coefficient are determined as in the previous work on the CH 4 /p-H 2 system. The potential is approximated to be proportional to the product of the polarizability of hydrogen molecule, the dipole-quadrupole polarizability of methane, and the inverse of the seventh power of the intermolecular distance between methane and hydrogen molecules. From the ratio of the potential coefficients of CH 4 and CD 4 the dipole-quadrupole polarizability of CD 4 is found to be 0.875 times that of CH 4 under the assumption that the quantum renormalization effect is negligible. A novel temperature dependence of the line shape of the 3 and 4 modes is discovered over the range of 4.5 to 8.0 K.

Tunneling chemical reactions in solid parahydrogen: Direct measurement of the rate constants of R+H2→RH+H (R=CD3,CD2H,CDH2,CH3) at 5 K

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The p-H 2 matrix is capable of providing not only high resolution spectroscopic information regarding embedded molecules but also subtle intermolecular interaction between trapped molecules and the matrix hydrogen molecule. 12,13,[15][16][17][18]21,22 The feasibility of the study of in-situ photolysis stems from the fact that molecules in solid p-H 2 happen to be free from the cage effect, which allows us to study photolytically produced fragments such as radicals originating from the parent molecule. 9,14,[23][24][25][26] In a previous paper we have observed Fourier transform infrared ͑FTIR͒ spectra of the CD 3 radical trapped in solid p-H 2 crystal.…”

High resolution infrared absorption spectra of methane molecules isolated in solid parahydrogen matrices

“…Although we have discussed the spectra obtained from rapid vapor deposited CH 4 In an attempt to directly observe the effects of increasing structural disorder on the spectroscopy of CH 4 /pH 2 solids, we performed a series of sample in vacuum depositions >2 El 1 | j -2,2-2) +12,2-2) +1-2,2,2) +12,2,2)], -)=|o,2,-2) + |0,2,2)],…”

“…8 " 10 Detailed analysis shows the existence of quantized CH 4 rotational states, with all spectral features consistent with trapping of CH 4 14 We define the crystal axis such that hydrogen molecules occupy the lattice points located at R, = /,a, + / 2 a 2 + / 3 a 3 where a, = a(i + j), In order to analyze the rovibrational states of methane interacting with parahydrogen, we need to consider the interaction which depends only on the orientation of methane. The interaction potential for a methane in an fee crystal has to be invariant under any symmetry operation of the extended group Gf cc .…”

SF 6 and its clusters in solid parahydrogen studied by infrared spectroscopy

“…This characteristic is demonstrated by our observation of the highly resolved rotation-vibration spectra of CH 4 and CD 4 in the p-H 2 matrix. [17][18][19] In the CH 4 /p-H 2 system we found that the matrix-isolated CH 4 monomer exhibits fine spectral splittings which provide us with quantitative information on the subtle intermolecular interaction between the CH 4 molecule and the matrix. 20 Not only the isolated monomer but also clusters of CH 4 show a rather rich spectral structure 21 that indicates that the parahydrogen matrix is also useful for the study of molecular clusters.…”