ABSTRACT
Plasma spectra initiated on single, optically levitated, micron-sized droplets of a glycerine-saturated brine solution are presented. The temporal development of the droplet plasma is monitored by observing neutral and once-ionized carbon and neutral sodium emission, and that of the air plasma by once-ionized nitrogen emission. The dependence of the plasma on laser parameters, such as wavelength and irradiance, is discussed.
ABSTRACT
Plasma spectra resulting from the irradiation of single, optically levitated glycerine droplets by an intense pulse from a Nd:YAG laser are presented. The temporal development of the plasma is studied by observing emission lines of neutral and once-ionized carbon and of once-ionized nitrogen. Stark shifts of the neutral-carbon lines are used to compute the plasma electron density. The droplet data are compared with similar data for laser-induced breakdown on a graphite surface.
ABSTRACT
The infrared and ultraviolet laser-induced photodestruction of diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP) has been surveyed. We used the excimer lasers ArF (193 nm), KrF (248 nm), XeCl (308 nm), and quadrupled Nd:YAG (266 nm) as well as a pulsed CO2 laser. Samples were irradiated in the vapor and liquid phases. Photodissociation was observed at all irradiation wavelengths, being most efficient when ArF irradiated DIMP or DMMP in the vapor phase in the presence of air or oxygen. Pulsed, focused CO2 radiation led to multiple photon dissociation and pyrolytic destruction. Light hydrocarbon gases were the principal decomposition products. Hydrogen, CO, CO2 and water were also detected. The residual liquid is likely to be a phosphorus-bearing acid.
Subject(s)
Lasers , Organophosphorus Compounds/radiation effects , Photochemistry , Spectrophotometry, Infrared , Spectrophotometry, UltravioletABSTRACT
Recently a variety of array detectors have been used in the focal plane of Czerny-Turner plane-grating spectrometers. The output signals have been coupled to a variety of storage units, resulting in optical multichannel analyzers (OMA). We present a clarification of the method for calculating the dispersion of this instrument, as well as a table of useful spectroscopic parameters for spectrometer-detector array combinations.
ABSTRACT
The (12)CF(4) molecule has been made to lase at various wavelengths in the 16-microm v(4) + V(2) ? V(2) band by pumping in the 9-microm 0 ? V(2) + V(4) band with (12)C(16)O(2) lines. The strongest reported (12)CF(4) laser line occurs at 615.06 cm(-1) and is pumped by 9R12 [9-microm band, R(12) line]. We have measured, by two techniques, the absorption of (12)CF(4) in 9R12, and also in 9R10 and 9R18, which are known to result in weak 16-microm laser transitions. This was done both at room temperature and at an estimated 100 K, and striking changes in spectral features were noted as the temperature was lowered. For the 9R12 laser line, we find a (12)CF(4) feature located 30 +/- 3 MHz to the high-frequency side of line center, with a peak absorption coefficient of 5 x 10(-4) to 9 x 10(-4) cm(-1) Torr(-1), depending on temperature. By contrast, there are only weak (12)CF(4) features within +/-40 MHz of the 9R10 and 9R18 laser-line centers, and the absorption coefficients of those features are 1 x 10(-4) to 2 x 10(-4) cm(-1) Torr(-1).
