• Chintan Gupta

      Articles written in Journal of Chemical Sciences

    • Maximization of yield of C-13 isotope by multiphoton dissociation of Freon-22 using high average power TEA CO2 laser

      Manoj Kumar Anant Deshpande Chintan Gupta A K Biswas A K Nath

      More Details Abstract Fulltext PDF

      Selective multi-photon dissociation (MPD) of Freon-22 (CF2HC1) molecules has been carried out using a TEA CO2 laser at various CO2 laser lines (9P(20)-9P(26)) in order to maximize the yield of C-13 isotope in the product (C2F4) at an enrichment factor of 100. The effects of laser pulse tail due to the presence of N2 in the laser mixture on the enrichment factor and yield of C-13 are investigated. It is found that the addition of a small amount of N2 is possible in the laser mixture without a significant drop in the yield at desired enrichment factor. Addition of a small amount of N2 improves the laser efficiency considerably. At a given pulse energy, a slight change in the near field intensity distribution of a laser severely affects the selectivity of C-13 isotope. The computed far-field intensity distributions of the measured near-field intensities show marked spatial variation in the focal spots that leads to a drop in selectivity. For macroscopic production of C-13 isotope a simple and novel multi-pass cavity has been designed and tested to focus the energy repeatedly keeping the optimum fluence constant at each focal spot.

    • Yield and enrichment studies of C-13 isotope by multi-photon dissociation of Freon-22 at low temperatures

      Manoj Kumar Anant Deshpande Chintan Gupta A K Nath

      More Details Abstract Fulltext PDF

      Multi-photon dissociation of Freon-22 (CF2HC1) at low temperatures has been carried out to separate the C-13 isotope using a TEA CO2 laser. Yield and enrichment of C-13 isotope in the product C2F4 are studied at 9P(22) laser line as a function of temperature (−50°C to 30°C). It is observed that at a given fluence when the temperature is lowered the yield decreases and the enrichment factor of C-13 increases.

      Room temperature irradiation of CF2HC1 towards the blue edge of C-13 absorption (i.e. at 9P(20) laser line) gives low yield of the product (C2F4) at a fluence, which produces the desired enrichment factor of 100. An increase in fluence gives very high yield of C2F4 but the enrichment factor is very low. Irradiating CF2HC1 at a temperature of −10°C enhances the enrichment factor to 100 and the yield obtained is comparable to that towards the red edge of C-13 absorption (i.e. at 9P(26) laser line).

      At a given enrichment factor higher enrichment efficiency is achieved when CF2HC1 is irradiated at lower temperature.

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