Direct experimental evidence of the hyperfine predissociation of molecular iodine using a saturated absorption experiment

A saturated absorption technique using an actively stabilized C.W. dye laser has been used to study the hyperfine structure of some lines lying in the 9-3, 10-3, 11-3, 11-4, 12-3 bands of the B-X system of molecular iodine. The comparison of the different spectra shows that the intensities of the different hyperfine components of one line deviate from the 2F + 1 proportionality when 'v decreases towards the value 'v=6 where the potential curves of the ³Π⁺₀ and 1u states are crossing. The preliminary experimental results concerning the hyperfine component intensity variations versus the quantum numbers 'v, J and F give a direct qualitative support to the recently reported hyperfine predissociation in I₂.     

An introduction to laser spectroscopy: Two cw-laser experiments

The principles, techniques and apparatus of two demonstration experiments using a tunable cw-laser are described. In the first experiment a passive external cavity enhanced the intensity of an incident laser beam enough to generate easily detected second harmonic UV radiation. The experiment also showed how to lock the frequency of one cavity to that of another. The second experiment used laser saturation spectroscopy to obtain sub-Doppler resolution and thereby exhibit the hyperfine spectrum of iodine molecules.     

Experimental method for the measurement of hyperfine transition saturation intensities in a gaseous medium

A laser system capable of generating picosecond pulses of 2 ps duration and peak powers of up to 50 MW, tunable throughout the emission spectrum of the lasing medium is described. The system consists of a cw dye laser which is tuned and is actively mode-locked by means of a novel interferometer. Single-pulse amplification is achieved via a two-stage N₂-laser-pumped amplifier arrangement. One of the most attractive features of the system here described is its inherent versatile broad tunability, which should allow, with different lasing media and pump sources, ps pulse generation from 400 to 700 nm using the same interferometer device.     

Picosecond saturation spectroscopy in microemulsions

We report on a first application of picosecond spectroscopy in the field of microemulsions. First results are given about the reorientation and absorption recovery kinetics of DODCI localized in the core of inverted micelles containing methanol. The experimental technique is the Absorption Saturation. The isotropic and anisotropic parts of the saturated absorption are detected with a time resolution of a few picoseconds.     

Saturated absorption experiments using a free running CW dye laser

The hyperfine structure of some new iodine lines has been observed over the tuning range of Rhodamine 6G (5800–6200 Å), using a free running, single mode cw dye laser. The resolution obtained in this experiment allowed to calculate the hyperfine constants of the excited state (³π₀⁺) of iodine with an accuracy of 2% for the quadrupole coupling constant and 50% for the magnetic one.     

New lasers and laser schemes

Conclusion We have demonstrated the existence of an anomalous polarization coupling mechanism present in the injection locked TEA CO₂ laser. As a direct consequence of this work, a new injection technique has been formulated which permits efficient injection coupling and maximises energy extraction whilst eliminating the detrimental optical feedback effects to which other injection locking systems are prone.Supported by the Office of Naval Research and the National Science Foundation     

Effects of modulation on signals obtained in saturated absorption spectroscopy experiments

An analysis of the useful signals detected in saturated absorption spectroscopy experiments is given. Both Gaussian and plane-wave fields are considered. The various cases of unmodulated, square-wave modulated and sinusoidally modulated saturating beams are examined. It is found that square-wave and sinusoidal modulations give different results. The first is identical to no modulation, and detection at the fundamental frequency records a fraction of the total signal which is also a square wave. The second gives fundamental or higher-harmonic signals each with a very different dependence on the saturation parameter. The signal at the fundamental saturates faster and more completely than that for square-wave modulation. The results suggest experimental methods for the determination of the absolute value of the saturation parameter.