Cavity ringdown spectroscopy of thin films in the mid-infrared.
To demonstrate the potential of the cavity ringdown technique in mid-infrared spectroscopy of thin film samples, we measured absorption losses in a C60 film on a BaF2 substrate using a tunable optical parametric amplifier source. With a Brewster angle sample geometry, we achieved a fractional loss sensitivity as small as 1.3 x 10(-7) with 1.5 cm(-1) resolution, an improvement in sensitivity of 2 orders of magnitude compared to standard Fourier transform infrared methods. At an absorption sensitivity of 5 x 10(-7), spectra of several C60 overtone lines were recorded.
Marcus
George A
GA
Department of Physics, Stanford Free Electron Laser Center, Stanford University, California 94305-4085, USA. gamarcus@stanford.edu
Schwettman
H Alan
HA