Berlin 2005 – scientific programme
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MO: Molekülphysik
MO 36: Experimental Techniques
MO 36.5: Talk
Monday, March 7, 2005, 17:30–17:45, HU 2097
A narrow-band Titanium:Sapphire pulsed laser: application to deep-UV Cavity Ring Down Spectroscopy — •Sandro Hannemann, Eric-Jan van Duijn, and Wim Ubachs — Laser Centre, VU Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
We present an injection seeded gain switched Titanium:Sapphire (TiSa) oscillator pumped by the second harmonic of a Q-switched Nd:YAG laser. Typically, it produces nearly Fourier limited pulses of 40 MHz bandwidth. A bowtie TiSa amplification stage is available to enhance the pulse energies up to 30 mJ. Nonlinear upconversion to the fourth harmonic allows for a continuous tuning range of 216 - 196 nm in the deep-UV (DUV), making the laser system versatile and ready for use in a wide variety of spectroscopic applications. Here, the technique of cavity ring down spectroscopy (CRDS) was extended to unprecedented short wavelengths in the DUV. Using CRDS, extensive spectroscopic studies of the very weak B3Σu− – X3Σg−, v=(0,0), (1,0), (2,0), (2,1) Schumann-Runge bands in molecular O2 including the isotopomer 18O2 were performed, yielding improved values for rotational and fine structure molecular constants of the excited B3Σu−, v=0−2 states. From a combination of CRDS and LIF detection, accurate information on collisional effects and fine structure dependent predissociation was obtained.