Measurement of electron transport coefficients in tetraethoxysilane by a double-shutter drift tube method

The ratio of the Townsend first ionization coefficient to the gas density , the mean-arrival-time drift velocity and the product of the longitudinal electron diffusion coefficient and the gas density in tetraethoxysilane (TEOS) vapour have been experimentally determined over a wide range of E/N from 14 to 6000 Td by a double-shutter drift tube technique using an arrival-time spectra (ATS) analysis. The result shows that the present values of are in excellent agreement with those previously measured by the steady-state Townsend method in an E/N range of 450 - 2000 Td. Values of and in the TEOS vapour are reported for the first time in the present paper. It is revealed that takes an almost constant value at 140 Td < E/N < 300 Td but monotonically increases in the other E/N ranges in the present measurement. The ratio of the longitudinal diffusion coefficient to the electron mobility is also deduced. The result shows that the mean electron energy in the TEOS vapour is very low, which suggests that inelastic collisions between electrons and the TEOS molecule occur more frequently even in a low-electron-energy region.