Cell walls, interaction with laser

Instead of using a CO2 laser as excitation source in the PA scheme, a CO laser offers the opportunity to measure trace gases (Bijnen et al. 1993). The CO laser emits radiation between 1260 and 2080 cm" at about 250 transitions (Av = 1 ). Single line lasing is achieved by cooling the discharge tube of the laser with liquid nitrogen. To increase the available laser power to 40 W the PA cell is positioned in the cavity of the laser. Care is taken to avoid interaction of laser radiation and cell walls... 

---