Gas spectrometry based on a pyroelectric thin film array

We present a far infrared gas spectrometer which uses a thin film pyroelect ric detector integrated on silicon. The detector is in-house fabricated and consists of 1 x 50 elements of sol-gel deposited, zirconium rich lead tita nate (PZT) which are suspended on a submicron membrane for thermal insulati on. The detector shows a detectivity of 16 mu A/W and is mounted into a Ori el monochromator fitted with gratings for the 3-5 mu m and the 8-12 mu m ra nge, respectively. The infrared radiation is emitted by a hot filament and chopped mecanically with a frequency of 10 Hz. Absorption spectra of CO and CO2 gas as examples for the 3-5 mu m wavelength range show detection limit s of 15 ppm for CO2 and 200 ppm for CO. Line shape investigations show that the cross sensitivity of our instrument can be neglected. In the 8-12 mu m wavelength range, we present absorption measurements for butane gas and N2 O, respectively.