Experimental study on an all gas-phase iodine laser using microwave discharge of Cl2/He as a Cl atoms source.
Microwave discharge of a Cl2/He mixture as a simple, clean and efficient Cl atom generator was used for an all gas-phase iodine laser study. Sufficient NCl(a1Delta) was produced through the reaction of HN3+2Cl-->NCl(a1Delta)+HCl+N2. The energy transfer reaction of I(2P3/2)+NCl(a1Delta)-->I(2P1/2)+NCl(X3Sigma) was observed. A population inversion was observed directly by using a 1315 nm tunable diode laser by scanning the entire line shape of the (3,4) hyperfine transition of iodine, and a small signal gain of 5x10(-5) cm-1 was obtained.
Energy transfer from chloroimidogen (a1.DELTA.) to iodine atoms
Mixtures of CH 2 I 2 and ClN 3 are photolyzed at 193 nm to produce iodine atoms and NCl(a 1 A3), respectively. The collisional excitation of the iodine atoms to the 5 2 P 1/2 state is readily observed from the time profile of chemiluminescence from this species. From a steady-state treatment of the intensities, the rate constant for the specific energy-transfer process (i.e., the excitation of the I 2 P 1/2 state) is determined to be k=(1.8±0.3) X 10 -11 cm 3 s -1
Quenching rate constants for NCl(b 1Σ+) and PCl(b 1Σ+) and radiative lifetimes of NCl(b 1Σ+), PCl(b 1Σ+) and PBr(b 1Σ+)
NCl(b 1Σ+), PCl(b 1Σ+) and PBr(b 1Σ+) molecules have been generated in a flow reactor by passing dilute flows of NFCl2, PCl3 and PBr3 in He through a dc discharge, and the total rate constants for quenching of NCl(b 1Σ+) and PCl(b 1Σ+) by several diatomic and small polyatomic molecules have been measured at 300 K. Except for O2, NO2 and molecular halogens, the rate constants are in the 10–13– 10–14 cm3 molecule–1 s–1 range. The dependence of the rate constants on the properties of the reagent suggests that the dominant quenching mechanism for PCl(b) and NCl(b) is electronic-to-vibrational (E–V) energy transfer with the a 1Δ state as the product, just as for the reactions of NF(b 1Σ+) and PF(b 1Σ+). The rate constants for quenching of NCl(b 1Σ+) and PCl(b 1Σ+) by O2 are 1.0 × 10–12 and ⩽ 10–15 cm3 molecule–1 s–1, respectively, and are in accord with an electronic-to-electronic (E–E) energy transfer with the final states being O2(b 1Σ+)+ NCl(X 3Σ–) or PCl(X 3Σ–). Formation of PBr(b 1Σ+) from the PCl(b 1Σ+)+ Br2 reaction was observed, and quenching of PCl(b 1Σ+) by F2, Cl2 and Br2 proceeds by a chemical mechanism with rate constants of 2.3 × 10–12, 0.79 × 10–12 and 16 × 10–12 cm3 molecule–1 s–1, respectively. The radiative lifetimes for NCl(b 1Σ+), PCl(b 1Σ+) and PBr(b 1Σ+) are 2.0 ± 0.4, 4.9 ± 0.8 and 0.8 ± 0.2 ms, respectively, as determined from the decay of the respective b 1Σ+→ X 1Σ– emission intensities along the flow reactor.