Thomas L. Henshaw

A new energy transfer chemical laser at 1.315 μm

Abstract : CW laser action has been demonstrated on the electronic I(*) - I transition of atomic iodine at 1.315 microns from the NCL(a) + I energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3, was injected into a flow of iodine and chlorine atoms. The measured laser output power was 180 mW.

The Measurement of Gain on the 1.315 Micrometers Transition of Atomic Iodine in a Subsonic Flow of Chemically Generated NCl(a(1) delta)

Abstract Gain is measured on the electronic I( 2 P 3/2 )– I ∗ ( 2 P 1/2 ) transition of atomic iodine at 1.315 μm when hydrazoic acid HN 3 is injected into a flow of iodine and chlorine atoms. The inversion was generated in a transverse subsonic flow device that produced electronically excited I ∗ ( 2 P 1/2 ) atoms from the efficient energy transfer reaction between NCl(a 1 Δ ) metastable and ground state I ( 2 P 3/2 ) atoms. The population inversion was directly observed using a 1.315 μm tunable diode laser that scanned the entire line shape of the (3,4) hyperfine transition of iodine.

Characterizing Fluorine and Chlorine Atom Flow Rates Using Iodine Atom Spectrometry

The production of F and Cl atoms in an electrical discharge of F 2 or Cl 2 has been examined in a flow reactor. A tunable diode laser was used to probe the concentration and translational temperature of I atoms produced by F and Cl atom reactions with HI. Kinetic modeling codes were used to determine the discharge efficiencies from the titration plots and the observed trends for atom concentration as a function of F 2 or Cl 2 and pressure. These calculations indicate that the de discharge used in these experiments is 100% efficient for F 2 flow rates ≤0.5 mmol s -1 and reactor pressure ≤20 torr. The highest F 2 -free F atom flow rate that we can generate is 1.0 mmol s -1 . Preliminary data for the Cl 2 discharge indicate that this is a much less efficient source of Cl atoms with yields of less than 50%.

Recent Progress in the Development of a Multi-Watt All Gas-Phase Iodine Laser (AGIL)

Recent results in the development of a multi-watt All Gas-phase Iodine Laser (AGIL) are presented. A description of the subsonic hardware used to produce NCl(a 1 Δ), direct measurements of I*( 2 P1/2) - I( 2 P3/2) small signal gain, and parametric studies to optimize the gain are described.

Measurement of gain on the 1.315-μm transition of atomic iodine as produced from the NCl(a1Δ) + I(2P3/2) energy transfer reaction

A direct measurement of gain on the electronic I (2P3/2) - I*(2Pi/2) transition of atomic iodine at 1.315 jam using tunable diode laser is demonstrated. The population inversion results from the efficient energy transfer between NCI (alA) metastables and I (2P3/2) atoms. Ground state iodine atoms and NCI (a1 A) metastables are produced in a transverse subsonic flow device from the stepwise reaction of Cl atoms with HI followed by the reaction of Cl with azide (N3) radicals, respectively. Under current experimental conditions, a gain of 0.020%/cm is obtained and appears to be limited by reagent number density. A kinetic model was constructed to simulate the experimental gain profile using a mechanism consisting of fully coupled finite rate chemistry and 1-D fluid dynamics. Good agreement with experimental and theoretical calculations are obtained. Keywords: Gain, population inversion, atomic iodine, NCI (a*A) metastables, azides, energy transfer

The direct observation of gain on the 1.315 μm transition of atomic iodine produced by the energy transfer from NCl(a1Δ) to I(2P3/2)

Gain between the I(2P3/2) and I*(2P1/2) states of atomic iodine at 1.315 μm was detected in a transverse subsonic flow reactor that produced electronically excited I*(2P1/2) atoms from the efficient energy transfer reaction between NCl(a1Δ) metastables and ground state I(2P3/2) atoms. The population inversion was directly observed using a 1.315 μm tunable diode laser that scanned across the entire I(2P3/2)−I*(2P1/2) hyperfine transition with complete resolution.

Temperature dependence of the C1+HN3 reaction from 300 to 480 K

The rate constant for Cl + HN3 over the temperature range 300-480 K has been studied in a flow reactor. Based on the rate of loss of HN3 and the rate of NCL(a1(Delta) ) generation, the temperature dependence of this reaction is described by the collision theory expression 1.2 +/- 0.3 X 10-11 T0.5 exp(-1514 +/- 93/T), with E0 equals 3.0 +/- 0.2 kcal mol-1 or an Arrhenius fit k(T) equals 2.0 +/- 1.0 X 10-10 exp(-1452 +/- 150/T) with Ea equals 2.9 +/- 0.2 kcal mol-1.