M. N. Ediger

CdI and CdBr photodissociation lasers at 655 and 811 nm: CdI spectrum identification and enhanced laser output with 114CdI2

Lasing on the B→X bands of CdI at 655 nm and CdBr at 811 nm has been obtained by photodissociating CdI2 and CdBr2 with an ArF laser. Also, the CdX (X = I, Br) B‐state radiative lifetimes and CdX2 quenching rate constants were found to be 32±3 ns, (9.2±1.1)×10−10 cm3 s−1, 25±4 ns and (7.9±3.3)×10−10 cm3 s−1, respectively. After synthesizing and photodissociating 114CdI2, the 114CdI laser spectrum was identified as arising from v′ = 0−2→v\ = 61, 62 transitions of the B→X band. The use of a single isotope of Cd (i.e., 114Cd) was also found to quadruple the energy output of the CdI laser and to make possible a dual‐wavelength metal‐halide laser, one operating simultaneously in the red (CdI) and near‐infrared (CdBr).

Excitation spectra of the np 3Πg, n′p 3Σ+g ←5s 3Σ+u(1u,0−u) Rydberg series of Kr2

Excitation spectra of the 5s 3Σ+u(1u,0−u) state of the Kr2 molecule have been obtained in the wavelength interval 335≤λ≲545 nm by monitoring atomic Kr emission at 758.7 nm (5p[1/2]0→5s[3/2]1) that accompanies dye laser excitation of the neutral excited molecule. The dominant peaks in the spectrum are identified as arising from np 3Πg←5s 3Σ+u Rydberg transitions where 7≤n≤18. The series limit and quantum defect δ for this series have been determined to be 28 471.9±3.9 cm−1 (351.12±0.05 nm) and 2.629±0.004, respectively, and the vibrational frequency ωe of the 5s 3Σ+u(1u,0−u) excimer has been estimated to be ∼195 cm−1. All of the observed Rydberg states have an A 2Σ+1/2u[1(1/2)u] ion core. Comparison of the np 3Πg←5s 3Σ+u series limit and the ionization potential of  Kr* 5s[3/2]2 shows that the A 2Σ+1/2u ground state dimer ion is ∼0.55 eV more deeply bound than is the Kr2 5s 3Σ+u neutral species. Also, dissociation energies of the np 3ΠgRydbergs are shown to be nearly identical to that of the A 2Σ+1/2u dime...

Absorption of electronically excited Xe2Cl in the ultraviolet

The absorption cross section for the lowest‐lying, bound excited state (4 2Γ) of Xe2Cl has been measured at several wavelengths in the ultraviolet (UV). Temporally isolating the excited Xe2Cl species in Xe/Cl2 gas mixtures has been accomplished by producing XeCl molecules in the B state by photoassociation [Xe+Cl+ℏω → XeCl(B)] at λ=308 nm. Collisional mixing of the lowest lying ion pair states of the excimer subsequently forms the XeCl species in its C state. Following the formation of Xe2Cl* from XeCl(B,C) by a three‐body collision, the long radiative lifetime of the trimer (>200 ns) relative to those for the XeCl B and C levels is exploited to ensure that the triatomic molecule is the predominant species when the experiments are performed. A second UV laser pulse depletes the Xe2Cl(4 2Γ) population by photoexcitation [as evidenced by the sudden suppression of the 4 2Γ → 1 2Γ blue‐green (λ∼485 nm) fluorescence] and the absorption cross section is determined from the dependence of the degree of fluorescen...

Quenching kinetics and small signal gain spectrum of the ZnI photodissociation laser

Abstract By photodissociation ZnI 2 with 193 nm (ArF) laser radiation, the rate constants for quenching of the upper and lower energy levels of the ZnI (B → X) laser by ZnI 2 have been measured to be (1.7 ± 0.2) × 10 -9 and (1.4 ± 0.4) × 10 -9 cm 3 s -1 , respectively. Although the former rate constant was found to be laser intensity-dependent for I ⪆ 10 5 W cm -2 , the ZnI(B) state radiative lifetime was determined to be 26 ± 4 ns. Also, the small signal gain coefficient, g 0 , of this molecular laser has a peak value of ⋍ 15% cm -1 at λ ⋍ 602 nm and exceeds 5% cm -1 for 591 nm ≤ λ ≤ 608 nm for a potential tuning range of at least 170 A.

Spectroscopy and efficiency of the 200 HgBr 81 and 64 ZnI photodissociation lasers

The spectra of the200HgBr81and64ZnI lasers were recorded following 193 nm (ArF) photodissociation of the corresponding triatomic salts and the dominant line in the200HgBr81spectrum is tentatively assigned to the (0, 23) transition of the B \rightarrow X band. The use of200HgBr 2 81rather than the natural abundance salt was found to increase the HgBr lasers conversion efficiency by 15 percent while64ZnI 2 more than doubled the ZnI laser output.

Two and three photon ionization of xenon

Two and three photon ionization of Xe has been studied using excimer lasers. Employing a microwave bridge to determine the temporal behavior of the absolute photoelectron density, the cross‐section for two photon ionization of Xe at 193 nm has been measured to be (4±1)⋅10−32 cm4−W−1. An order of magnitude improvement in the peak electron density is realized by ionizing Xe with two XeF (351.1 nm) and one ArF (193.3 nm) photons. This process is resonantly enhanced by the 6p[1/2]0 level of Xe. The strong, selective pumping of this state has resulted in the observation of stimulated emission on the Xe {6p[1/2]0→6s[3/2]11} transition at 828.0 nm−the first optically pumped rare gas laser.

Photodissociation of Xe+2 and Kr+2 in the ultraviolet: Application to Xe2Cl formation kinetics

An optical approach to monitoring the population densities of the rare gas dimer ions Xe+2 and Kr+2 in real time has been developed. An excimer laser is used to photodissociate the Rg+2 ion via the 1(1/2)u→2(1/2)g UV absorption band and the resulting depletion of the molecular ion population is detected by observing the 6p→6s fluorescence of the neutral xenon or krypton atom. This technique has been applied to examining the formation kinetics of the triatomic rare gas‐halide molecule Xe2Cl (2Γ).