Knowledge Bank

Molecular beams using multitude capillary arrays when crossed by laser beams provide a simple means for studying sub-Doppler spectroscopic features in the spectra of lighter molecules. The high resolution spectra of the symmetric CF stretching mode of $CF3Cl$ in the region of the Q branch $(\sim 1108.2cm-1)$ have been obtained under static cell conditions using an LS-3 tunable semi-conductor diode laser system. Even at very low pressures $(\sim 0.1Torrorless)$ several of the lines show broad unresolved features. When the absorption is monitored in a molecular beam, for driving pressures of the order of a few Torr, several of these features split and show fine structure. The diode laser is tuned over a range of $0.1cm-1$ and propagates $\sim 1cm$ below the collimators. The strong features in the spectra are attributed to the Q branch (J & K structure) of the $CF335Cl$ isotopic molecule. Weak contributions from $CF337Cl$ as well as hot bands is also to be expected. To help in the preliminary analysis of the data computer simulation of the spectrum has been carried out.