A flow system for production of diatomic metal oxides and halides is described. Molecules are produced by reacting metal vapor in a flowing, inert gas with a suitable oxidizer. Product molecules are frequently formed in electronically excited states, making this system particularly useful for optical emission spectroscopic studies. Specific advantages are: (a) large number of reactant products; (b) little thermal excitation in the reaction region; (c) spectra uncluttered by emission from undesirable species; and (d) in many cases, formation of molecules in electronically excited states not produced or detected in other sources. Also discussed is a variation of the design which is used to produce small metallic particles. These particles are formed by homogeneous nucleation of the metal vapor and range in size from 5 to 500 nm.

Diatomic barium monohalides (BaX) have been produced in the gas−phase reaction of Ba, entrained in a flowing inert carrier gas, with F2, SF6, Cl2, Br2, and I2. Bright green chemiluminescent flames were observed at pressures from 0.1−10 torr. Emission spectra were obtained from 300−1200 nm. Near infrared emission from BaBr and BaI has been ascribed to transitions to the ground state from previously unobserved electronic states analogous to A and B states in BaF and BaCl. In BaBr, electronic state energies for B 2Σ+, A 2Π3/2, and A 2Π1/2 have been found to be 11 325, 10 604, and 9980 cm−1, respectively; in BaI, corresponding values are 10 417, 9921, and 9268 cm−1. BaX molecules are produced with moderate efficiency into lower lying electronic states (80%−98% in A and B) with an absolute efficiency of approximately 1 photon for each 100 reacted barium atoms. There is a small dependence on pressure with maximum yields occuring near 4 torr. Spectra of C 2Π−X 2Σ+ transitions show Boltzmann distributions in both vibration and rotation corresponding to population temperatures of approximately 3000 K for BaF and 2000 K for BaBr, BaCl, and BaI. Electronic population temperatures show trends similar to those observed in vibration and rotation.

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High-power laser emission has been observed from xenon fluoride (XeF) at 351.1 and 353.1 nm. A peak laser power of 0.5 MW was obtained by using a mixture of Ar, Xe, and NF3 in the ratio of 250 : 25 : 1 at a total pressure of 1.7 atm. The laser gas was excited by a 1-MeV 20-kA electron beam for a pulse duration of 20 nsec. Energy deposited in the gas by the electron beam was estimated to be 1 J which gives a laser efficiency of 0.5%. Using a coaxial electron gun, an 80-mJ 100-nsec pulse was obtained with an efficiency of 3%.

The Vertically Integrated Photon Imaging Chip (VIPIC) was custom-designed for X-ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time-and position-stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non-zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame-oriented detectors such as charge-coupled devices or conventional hybrid pixel detectors. This feature allows continuous acquisition of data with timescales from microseconds to hours. In this work VIPIC has been used to measure X-ray photon correlation spectroscopy data on polystyrene latex nano-colliodal suspensions in glycerol and on colloidal suspensions of silica spheres in water. Relaxation times of the nano-colloids have been measured for different temperatures. These results demonstrate that VIPIC can operate continuously in the microsecond time frame, while at the same time probing longer timescales.

Strong laser emission was observed in the 342-nm I2 band system from an e-beam–excited mixture of Ar and CF3I (250 : 1) at a total pressure of 10 atm. Laser emission occurred simultaneously at 342.0, 342.3, 342.4, and 342.8 nm with a peak power of 3.6 MW in a 10-nsec (FWHM) pulse.

Efficient high-power laser emission has been observed at 249 nm from a KrF excimer laser obtained by an electron-beam-pumped mixture of Ar, Kr, and NF3 (1300:130:1) at a total pressure of 2.25 atm. An energy of 1.5 J was extracted in a 125-nsec (FWHM) pulse from a 100-cm3 volume, using a coaxial electron-beam laser. Laser efficiency was estimated to be nearly 15% based on energy deposition in the gas. Over-all electrical efficiency was ∼1%.

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