J.H. Richardson

Time-resolved laser-induced fluorescence with high-performance liquid chromatography for analysis of polycyclic aromatic hydrocarbon mixtures

Abstract Time-resolved fluorescence is used to enhance the selectivity for polycyclic aromatic hydrocarbon mixtures by high-performance liquid chromatography. A pulsed laser is used as the excitation source. Only fluorophores with long fluorescence lifetimes (e.g. fluoranthene) are monitored if the delay between excitation and detection is sufficiently long. Limits of detection are of the order of 1–10 pg (5–50 fmol). The advantages are illustrated with a sample from the condensed steam distillate following a coal gasification experiment.

Sensitive assay of biochemicals by laser-induced molecular fluorescence.

Parts-per-trillion detection of several vitamins and amino acids has been achieved through the application of laser-induced molecular fluorescence techniques. Compounds which possess native fluorescence were investigated as well as nonfluorescent compounds which could be labeled with fluorescamine. In all cases the use of a pulsed laser as the irradiation source was shown to improve the minimum detectabilities by at least two orders of magnitude over those achieved with conventional light sources.

Near-infrared optical absorption in solid DT and T2

Abstract Near-infrared optical absorption has been detected for solid DT and T 2 samples. It is suggested that this absorption is due to electrons and/or ions resulting from the radioactive decay of tritium being trapped in the solid lattice.

Biochemical applications of a synchronously pumped krypton ion dye laser fluorescence system

Abstract A synchronously pumped krypton ion dye laser fluorescence system is shown to provide tunable, polarized, subnanosecond pulses at high repetition rates, modest peak powers, and low energy. Such a source is uniquely suited to fluorescence investigations of biochemical mechanisms. Applications of this fluorescence excitation source to analysis, life-time determination, and depolarization effects are discussed.

A mode‐locked krypton ion laser with a 50‐psec pulse width in the near uv

The mode‐locked near‐uv output from a krypton ion laser is characterized and shown to produce near‐transform‐limited picosecond pulses. Applications to time‐resolved fluoresence studies for chemical analysis are included.

Spectroscopic properties of gas: phase molecular ions

This review on spectroscopic properties of gas-phase molecular ions confines itself to molecular ions in the gas phase (except in some recent studies of laser-induced multiphoton ionization). Ion cyclotron resonance techniques are discussed in some detail. Other techniques discussed in lesser detail are beam foil spectroscopy, photoelectron spectroscopy, crossed-beam studies, photoionization, and conventional emission-absorption spectroscopy. 248 references are cited.

Laser-induced photoelectrochemistry: time-resolved luminescence studies of cds electrodes

Abstract The luminescence lifetime of a tellurium-doped CdS electrode in alkaline sulfide electrolyte has been determined. The decay is not a single exponential; the nominal lifetime varies from ⩽ 10 to⩾ 250 ns as a function of laser power, wavelength, and electrode potential. The results are discussed relative to recent steady-state luminescence measurements and time-resolved coulostatic photoelectrochemicai measurements.

Recent pulse width and linewidth measurements on the mode-locked Kr(+)-ion laser.

The output power of six lines is studied for Spectra-Physics Kr/sup +/-ion lasers models 171k. (AIP)

Experimental evidence of laser‐induced separations in bulk gas mixtures

Radiation from a cw CO2 laser is used to separate SF6 molecules from helium molecules in a bulk mixture of each, by resonant radiation pressure. These experimental results demonstrate that selective absorption of radiation can cause physical separations of molecules within a diffusion‐limited geometry.