Reinvestigation of the HSiCl electronic spectrum: Experimental reevaluation of the geometry, rotational constants, and vibrational frequencies

Abstract

The ground and first excited singlet states of monochlorosilylene have been reexamined using pulsed discharge jet and laser induced fluorescence techniques. HSiCl and DSiCl have been produced by an electric discharge through SiHCl3 and SiDCl3 vapor in argon. The 000 band rotational constants of four isotopomers of HSiCl and the harmonic force fields for both states have been combined to obtain the following estimates of the equilibrium structures: r′′(SiCl)=2.067(3) Å, r′′(SiH)=1.525(5) Å, θ′′(HSiCl)=96.9(5)°, r(SiCl)=2.040(3) Å, r(SiH)=1.532(8) Å, and θ(HSiCl)=118.1(5)°. Previous anomalies in the ground-state structure and the excited-state vibrational frequencies have been resolved. The radiative lifetime of the 480–400 nm (Ã 1A′′–X̃ 1A) band system of HSiCl has been measured to be 432±20 ns.

Emission spectroscopy, harmonic vibrational frequencies, and improved ground state structures of jet-cooled monochloro- and monobromosilylene (HSiCl and HSiBr)

“…3, 6 In the least squares analysis, the harmonic frequencies were given an estimated uncertainty of Ϯ1 cm Ϫ1 , except for 3 of HSi 79 Br which was estimated to be Ϯ3 cm Ϫ1 , due to use of the DSi 79 Br value for x 33 0 . The normal coordinate analysis was set up using internal coordinates and the force constants were refined using the Hedberg and Mills ASYM20 program.…”

“…A set of average rotational constants (B z ) was obtained by adding the harmonic contributions to the ␣ constants to the previously known zero-point rotational constants. 3, 6 The structural parameters for each HSiX molecule were refined by fitting the planar moments obtained from the B z constants using Rudolph's RU111 program. 29 The Si-H bond contraction upon deuteration was calculated from the force field and the appropriate diatomic molecule constants, as in our previous studies.…”

“…6 Tribromosilane was synthesized by passing HBr ͑Matheson͒ over a 10:1 mixture of Si ͑Aldrich͒: CuBr 2 ͑Baker͒ heated to 425°C. 22 The products were condensed at Ϫ50°C and the HSiBr 3 was separated by trap-to-trap distillation.…”

“…16,17 Recently, Nalda et al 18 reported observing strong emissions produced by UV photolysis of CES. Using the spectroscopic constants from our previous study, 6 they were able to assign the observed emission bands as due to the HSiCl radical.…”

Ab Initio Potential Energy Surfaces for Both the Ground (X̃1A′) and Excited (ALi1, Lin2, Xie3 2012Advances in Physical Chemistry33040View full textAdd to dashboardCite

“…The identification and quantification of such intermediates could help make these processes more efficient, so that they have attracted much attention in experimental and theoretical studies [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. However, because these radicals are typically short-lived and highly reactive, it is difficult to monitor them.…”