An efficient method for the rejection of fluorescence from picosecond time-resolved resonance Raman (ps-TR3) spectra, applicable also to ground-state Raman spectroscopy, has been demonstrated. The technique removes fluorescence from Raman light in the time domain using a Kerr gate driven by 110 μJ, 1 ps pulses at 800 nm and a repetition rate of 0.65 kHz, giving a response time of ∼ 3 ps, representing the highest time resolution achieved experimentally for rejecting fluorescence from Raman spectra. The effectiveness of the method is proven by measuring Raman solvent bands and ps-TR3 spectra of S1 p-quaterphenyl from solutions contaminated with the laser dye DCM using laser wavelengths which excite the dye and so produce intense fluorescence emission. The optical transmittances accounting for losses in the optical elements and losses due to incomplete polarization rotation in the Kerr medium in the open and closed states were 15% and 0.005%, respectively. The use of the gate in a time-resolved fluorescence measurement of DMABN is also demonstrated.

In the course of recent investigations of the laser-induced reactions of the alkyl alcohols, irradiations of methanol in the gas phase with a carbon dioxide (infrared) laser produced very interesting results. The principal product of the reaction, formaldehyde, spontaneously reacted with excess methanol to form methoxymethanol, a molecule about which very little is known. Initially, due to the presence of excess reactant still in the sample cell, the infrared spectra displayed the bands of the mixtures of both methanol and methoxymethanol, enabling this laboratory to report only the combined infrared spectra with three infrared bands assigned to methoxymethanol. Additional research utilizing hyphenated chromatographic/spectroscopic techniques significantly advanced this effort. A gas chromatograph interfaced with a mass selective detector (GC/MS) and another gas chromatograph interfaced to a gold-plated lightpipe (GC/FT-IR) enabled the recording of both mass and infrared spectra, respectively. After extensive and innovative research efforts, which included the use of novel subambient temperature lightpipe studies, this laboratory recorded the infrared spectra of isolated methoxymethanol, a scientific first. Research in this area is ongoing. This paper reports the experimental parameters and techniques as well as infrared and mass spectra of all molecules investigated, including methoxymethanol, formaldehyde, and methanol, including one deuterated species.

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Germanium and doped-germanium polycrystalline films were formed with the use of photolytic CO2 laser-induced chemical vapor deposition. The compounds which yielded germanium in large quantities were germane, ethylgermane, and diethylgermane. Triethylgermane produces germanium in trace quantities. Gas-phase reactions were monitored with the use of Fourier transform infrared spectroscopy, also used for identification of end products. Scanning electron microscopy was used for analysis of the films. The products identified on irradiation of germane were germanium and hydrogen, with conversion rates of 86%. On irradiation of diethylgermane and ethylgermane, ethylene, germane, germanium, and hydrogen were produced. Germanium films doped with cadmium and aluminum were produced successfully by the irradiation of germane mixtures containing dimethylcadmium or trimethylaluminum, respectively.