J.B. Atkinson

The 0+u(6 3P1)←X0+g spectrum of Hg2 excited in a supersonic jet

Abstract The 0 + u (6 3 P 1 )←X0 + g excitation spectrum of Hg 2 van der Waals molecules, produced in a pulsed free-jet supersonic expansion beam crossed with a pulsed dye-laser beam, was studied using He as a carrier gas. A well-resolved structure, arising from transitions between the vibrational levels of the lower and upper states, was recorded at various beam conditions. An analysis of the spectrum yielded the vibrational constants, dissociation energies, and the difference between the equilibrium internuclear separations for the molecule in the two electronic states.

Spectroscopy of the A0+ and B1 states in HgAr and HgNe

Abstract Excitation spectra of HgNe and HgAr van der Waals molecules were produced in a pulsed supersonic molecular beam crossed with a pulsed dye-laser beam. Bands arising from A0 + ← X0 + and B1 ← X0 + vibronic transitions were analyzed, yielding spectroscopic constants for HgNe and HgAr. A0 + → X0 + and B1 → X0 + fluorescence spectra of HgAr were also recorded, consisting of Condon internal diffraction patterns arising from bound-free decays of various vibronic states, together with vibrational components produced by bound-bound transitions. Term analyses of the spectra combined with computer-modeling calculations produced improved values of spectroscopic constants.

Laser spectroscopy of the 1Σ+u (4 1P) and 3Πu (4 3P) states in Zn2

Abstract The 0 + u (4 1 P) state of Zn 2 was excited near the crossing of the 1 Σ + u (4 1 P) and 3 Π u (4 3 P) states, using pump and probe methods with time resolution. A structured excitation spectrum was observed in the 530–570 nm region and is ascribed to the 3 Π u (4 3 P)← 3 Π g (4 3 P) vibronic transitions. A fluorescence spectrum which was emitted in the 250–306 nm region is believed to arise from the 1 Σ + u →X 1 Σ + g bound—free decay. It consists of a “Condon internal diffraction pattern” whose profile suggests that it was emitted from a high vibrational level ( v ′ = 19) of the 1 Σ + u state.

The rotationally resolved G0+u ← A0+g electronic spectrum of the (202Hg)2 excimer

Abstract Isotopically pure 202 Hg vapor, contained in a quartz cell, was irradiated with frequency-doubled 5140 A output from an Ar + laser, which caused the formation of Hg 2 A0 ± g excimer molecules by photoassociation. Simultaneous probe radiation from a ring dye laser scanned over a range 5400–6000 A, produced the G0 + u ← A0 + g excitation spectrum which consists of several hundred well-resolved rotational components that have not been previously observed. Two vibronic bands were subjected to a rotational analysis which yielded spectroscopic constants that are compared with some previously reported values.

Laser-induced 1Σ+u ← 3Πg excitation spectrum of Zn2

Abstract A structured excitation spectrum of Zn2 in the 420–470 nm region was registered in zinc vapor subjected to pump-and-probe excitation as the emitted bound—free fluorescence was monitored at 274 nm. The excitation and fluorescence spectra were interpreted as due to transitions involving the 1Σ+u (5 1S), 3Πg (4 3P), and X1Σ+g (4 1S0) states. An analysis of the vibrational structure yielded vibrational constants and relative energies for the 1Σ+u and 3Πg states.

Laser spectroscopy of the 3Σ+u(4 3P, 4 3P) state of Zn2

Abstract The doubly-excited 3Σ+u (4 3P, 4 3P) state of Zn2 was populated using pump and probe methods with time resolution. Structured excitation and fluorescence spectra were observed in the 300–330 nm region and are ascribed to 3Σ+u (4 3P, 4 3P)↔3Πg(4 3P) vibronic transitions, with partial resolution of the fine structure. An analysis of the spectra yielded the vibrational frequencies, relative energy, and relative equilibrium internuclear separations for the 3Σ+u and 3Πg states. The Zn2 excitation and fluorescence spectra contained a number of atomic lines whose origin was probed in a subsidiary experiment.

Laser-induced fluorescence from the 3Πu(43D) state of Zn2

Abstract The 3 Π u (4 3 D) state of Zn 2 was excited using pump and probe methods with time resolution. Structured excitation and fluorescence spectra were observed in the 325–360 nm region and are ascribed to 3 Π u (4 3 D)↔ 3 Π g (4 3 P) vibronic transitions. An analysis of the vibrational band structures yielded the vibrational frequencies, relative energy and relative equilibrium internuclear separations for the 3 Π u and 3 Π g states.

Laser-induced fluorescence of the Zn 2 excimer

Pump-and-probe methods of laser spectroscopy with time resolution were used to study fluorescence and excitation spectra arising from transitions involving the (1) product operator(u)(4(1)P), (3) product operator(g)(4(3)P), and X(1)Sigma(+)(g)(4(1)S) states for the Zn(2) excimer. An analysis of the vibrational bands yielded vibrational constants, relative energies, and relative internuclear separations for the (1) product operator(u) and (3) product operator(g) states.

The design of achromatic prism beam expanders for pulsed dye lasers

Abstract The design of achromatic prism beam expanders for use with pulsed dye lasers is considered. The designs concentrate on producing an achromatic output beam, collinear with the input beam, to facilitate the use of a calibrated sine-drive Littrow mounted grating. A number of different useful combinations are presented, and the performance of three of them is discussed.

A Fizeau wavemeter with single-mode optical fibre coupling

An improved Fizeau wavemeter for CW and pulsed laser wavelength measurements was developed, incorporating single-mode optical fibre coupling. The whole optical system is enclosed in an evacuated chamber and the optical fibre acts as a spatial filter, resulting in an improved performance and increased simplicity of alignment and operation. Wavelength measurements have been performed with an accuracy better than 1 part in 106 for CW lasers and 2 parts in 106 for pulsed lasers.