• M A N Razvi

      Articles written in Pramana – Journal of Physics

    • On the non-BoltzmannA-X emission in Na2 following laser excitation of theB state

      A Sharma G L Bhale M A N Razvi M N Dixit

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      A1Σu+-X1Σg+ emission in Na2 is observed following excitation ofB1πu by various lines of an argon ion laser. The excitation energy ofB1πu is collisionally transferred to the (2)1Σg+ which then radiatively populates theA1Σu+ state. The Na vapour is contained in a stainless steel crossed heat pipe with Ar buffer gas and temperature around 600°C. For all laser lines except 4579 Å, the coarse features ofA-X emission are independent of the laser wavelength. However, at high resolution the finer differences between different laser line excitation are explained. Variousv′-v″ transitions in this emission are identified. Computer simulation is presented to help explain some features of this emission.

    • Three photon resonant ionization in atomic potassium via S, P, D and F series Rydberg states

      A Sharma G L Bhale M A N Razvi

      More Details Abstract Fulltext PDF

      Single colour three photon resonant ionization (2 + 1) is observed in atomic potassium vapour in a heat pipe oven using an excimer laser pumped dye laser. Using wavelengths between 570 nm and 603 nm various2S and2D Rydberg states are populated by two photon excitation. Third photon of the same wavelength ionizes the atoms. Rydberg states up ton ⋍ 50 are observed. Electric field as low as 1 V/cm causes extensive Stark mixing of the states. This results in progressively higher three photon ionization signals via the perturbed2P and2F Rydberg states. The three photon ionization process is studied using both linearly and circularly polarized incident light. The experiment shows qualitatively that the2P Rydberg states are perturbed primarily by the2D states in the prescence of an external electric field and to a much smaller extent by2S states. This is also explained theoretically by calculating the Stark mixing coefficients under the Bates and Daamgard (1949) approximation. Implication for a similar effect in other alkali elements is discussed.

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