Piezoelectric detection of high vibrational overtones of liquid tetramethylsilane, tetramethylgermane, and tetramethylstannane

The liquid-phase high vibrational overtone spectra of (CH 3 ) 4 Si, (CH 3 ) 4 Ge, and (CH 3 ) 4 Sn have been recorded using piezoelectric detection. The overtones have been measured in the spectral regions of the C-H stretching modes corresponding to Δv=6 and 7. A technique is presented which uses a piezoelectric detector, lock-in ampIification, and a continuous wave dye laser modulated at frequencies from 10 to 120 kHz with an acousto-optic modulator