Flexural resonant samples for submonolayer measurements of oxygen on Si surfaces

Photothermal deformation measures optical energy absorption by thermal expansion of a solid. This work describes how deflection amplitude is increased by a factor of 104 by mechanically resonating thin bars in a flexural mode of vibration. Small (∼10-5-5×10-3 fractional) infrared optical absorptions from Si surfaces are reported in various reactive gases using a tunable CO2 drive laser. Alternately, conventional low-power light sources can be used to provide sufficient excitations for submonolayer infrared absorption measurements.