Nitrogen-pumped Dye Laser Research Articles

Wavelength tuning of nitrogen pumped dye laser

In this paper a method is described for continuous wavelength tuning of nitrogen pumped dye laser by changing the concentration of an additional dye in the lasing solution.

B3Π(0+) states of IF, ICl and IBr. Part 2.—Observation and analysis of the excitation spectra of IF and ICl

Narrow band tunable radiation from a nitrogen pumped dye laser has been used to excite fluorescence in the B3Π(0+)–X1∑+ systems of IF (430 to 500 nm) and of ICI (568 to 650 nm). The kinetically labile IF molecules were produced in a fast flow system by the rapid elementary reaction F + ICl → IF + Cl. No laser excitation or absorption spectrum of IF has been described previously. Onset of pre-dissociation has been observed at J′= 12, v′= 10 of IF B3Π(0+), and a new value for the dissociation energy of IF, D″0(IF)⩽(22 700 ± 15) cm–1, is reported. Criteria for the commencement of pre-dissociation in IF spectra are discussed. The mechanism of formation of the B and A states of IF in F2+ I2 systems is considered to arise from initial production of IIF, in the elementary step, I2+ F2→ IIF + F. Laser fluorescence of ICI from the excited B3Π(0+) state (v′= 0, 1, 2) has been observed. The 0–2 band of the B–X system of I35CI has been analysed, providing the first spectro-scopic constants for the level v′= 0 of the B state. A complete evaluation of constants for this shallow, weakly-bound state, has thus been possible. The onset of predissociation in ICI B3Π(0+) near J′= 70 of v′= 2 is discussed in the light of linewidth measurements of other workers.

Polarization and assignment of the two-photon excitation spectrum of benzene vapor

The two-photon excitation (TPE) of benzene fluorescence in the vapor phase at 60 torr is reported for the total-energy region from 38 086 cm −1 to 42 441 cm −1 using both circular and linear polarized light from a nitrogen-pumped dye-laser. The theory of the polarization dependence of the vibronic transitions in benzene is briefly reviewed, and it is seen how transitions involving vibrations of b 1u symmetry are expressly forbidden for this type of TPE experiment in which the two photons are identical. Five vibronic origins with distinctive rotational contours and polarization dependence are identified in the TPE spectrum. The υ 14(b 2u) vibronic origin at 1570 cm −1 (above the electronic origin of the IB 2u state) stands out very prominently in the linear polarized spectrum, but nearly disappears in the circular polarized spectrum. This striking polarization dependence indicates a significant contribution of A 2u electronic states to the intermediate states of this TPE vibronic transition. The relatively great strength of the υ 14 band may be due to vibronic borrowing by the b 2u mode from the ground electronic state (A 1g).

Subnanosecond pulses from a single-cavity dye laser

A simple nitrogen pumped dye laser is described which, sequentially in time, generates two pulses, one due to superradiance and the other to laser action. The duration of both the pulses can be changed continuously on a nanosecond time scale, down to a few tenths of a nanosecond for the superradiant pulse. Pulses as short as 0.4 nsec have been obtained for the superradiant beam.

Connections and disconnections on integrated circuits using nanosecond laser pulses

Nanosecond pulses from a focused nitrogen pumped dye laser have been used to connect and disconnect conductors on FET chips. Experiments on connections between n+ diffusion layers and aluminum, separated by an insulating layer of SiO2, show promise for high yield and reliability. The connections have Ohmic characteristics. Sectioned laser connections were examined with an electron microprobe and microscope in order to examine physical details of the connection process.

Sensitized fluorescence measurements using a pulsed dye laser

A method is presented for measuring the relative intensities of sensitized and resonance fluorescence in alkalis by using a pulsed nitrogen pumped dye laser and gating the output pulses from the photomultipliers. Measurements show the system to have a high signal-to-noise ratio and much improved sensitivity over previous methods.

The generation of tunable coherent radiation in the wavelength range 2300–3000 Å using lithium formate monohydride

The generation of continuously tunable UV radiation in the wavelength range 2300–3000 Å by frequency doubling the output of a nitrogen pumped dye laser is described. A lithium formate monohydride crystal 10 mm long yields a conversion efficiency of typically 2% at fundamental powers in excess of 50 kW and allows the generation of harmonic radiation at wavelengths 150 Å below those attainable using a refrigerated ammonium dihydrogen phosphate crystal.

The efficient generation of coherent radiation continuously tunable from 2500 Å to 3250 Å

The generation of continuously tunable UV radiation in the wavelength range 2500–3250 Å by frequency doubling the output of a nitrogen pumped dye laser is described. An ADP crystal 25 mm long yields 11% conversion to the UV at a fundamental dye laser power of 60 kW. The parameters affecting the conversion efficiency are discussed.