Stimulated stokes emission with a dye laser: Intense tuneable radiation in the infrared

Tuneable stimulated Stokes emission is generated at ≈2.9 μm in barium vapor with an oscillator-amplifier dye laser. The conversion efficiency is as high as 40% and the energy output as high as 30 mJ. The emission is tuneable over ≈100 cm^-1. At high vapor pressures the tuning profile is markedly asymmetric.     

On-line mass spectrometry in fermentation

The on-line application of mass spectrometry (m.s.) includes analysis of the fermentor gas phase by using a capillary inlet and analysis of the liquid phase by using membrane probes. Gas-phase measurements with a capillary inlet are fast and accurate for all gases of interest (O₂, N₂, CO₂, H₂, etc.). Liquid-phase measurements are done with steam-sterilizable membrane inlet probes, permitting direct analysis of dissolved gases and various volatiles. With these two inlets, automatic measurement of both the liquid and gas phases is possible when a microcomputer is used. This was applied to the batch fermentation of Bacillus subtilis. A further application of the membrane probe is evaluation of fermentation process state; this involves measuring the spectra of all detectable volatiles and correlating this information with the process state (e.g., product formation). Sufficient characteristic volatiles were found in various industrial fermentation samples. When mass spectra are treated by factor analysis, useful correlations are found with the product concentrations measured off-line. Calibration depending on the process conditions is necessary for this method, but it is widely applicable and allows automatic monitoring.     

Investigations of stabilizing additives. I. A model system for studying radical scavenging activity in solution

In the current study an electron spin resonance model system was developed to compare the thermal stability and radical scavenging activity of stabilizers in solution. High-resolution spectra and the influence of molecular structure on radical stability provided a basis for the interpretation of spin concentration data in the model system. A correlation was established between the radical scavenging activity measured in the model system and actual behavior in irradiated polypropylene formulations measured by radiation-induced degradation of mechanical properties.     

The vapor-phase infrared and Raman spectra of p-difluorobenzene (h4) and (d4)

This new study of the vapor-phase infrared and Raman spectra of p-difluorobenzene (h₄) and (d₄) includes assignments from the high-resolution electronic spectrum, from fluorescence spectra, and one assignment from the two photon electronic spectrum. A new set of frequencies and assignments has been made for the fundamentals of this important intermediate-sized molecule. The most important changes concern the assignments previously made for the lowfrequency a_u mode (ν₈), two members of the b_2u class (ν₁₉ and ν₂₀), and one very important change for the lowest frequency fundamental of the b_3u (out-of-plane) class (ν₃₀), which has been observed directly in the far infrared. The results are all corroborated by the assignments of the perdeuterated analog where changes in previous assignments of Fermi resonance pairs have also been made. Some interesting differences between the Raman spectra of the vapor and the liquid perproto compounds have not been adequately explained in this study.     

Quenching of N2(A3Σu+) by O2, O,N, and H

Metastable N₂(A³Σ_u⁺), υ = 0, υ = 1, molecules are produced by a pulsed Tesla-type discharge of a dilute N₂/Ar gas mixture. Rate coefficients for quenching these metastable levels by O₂, O, N, and H were obtained by time-resolved emission measurements of the (0, 6) and (1, 5) Vegard–Kaplan bands. In units of cm³/mole · sec at 300°K and with an experimental uncertainty of ±20%, these rate coefficients for N₂(A³Σu⁺) are Within the limits of error these coefficients apply to quenching N₂(A³Σ_u⁺) υ′ = 1 as well.     

On-line searching: costly or cost effective? A marketing perspective

The value of acquiring and using information is not well understood. Decisions to purchase information are made on the basis of the perceived need for the information, the anticipated benefit of using it, and the price. The current pricing of on-line information services, which emphasizes the connect hour as the unit of price, does not relate the price of a search to the value of a search, and the education programs of on-line vendors and database suppliers concentrate on the mechanics of information retrieval rather than on the application of information to the customer's problem. The on-line information industry needs to adopt a strong marketing orientation that focuses on the needs of customers rather than the needs of suppliers or vendors.     

Tunable,continuous-wave,ultra-violet radiation around 300 nm by frequency-doubling a rhodamine 6G dye laser

By frequency doubling a cw Rhodamine 6G dye laser using an ADP crystal placed in the laser cavity, in excess of 30 mW of cw uv radiation has been generated. The radiation is tunable over the range 285–315 nm. The ADP crystal is cut with Brewster angle ends, and is located at the focus of cavity compensated for coma and astigmatism. Conversion efficiency is shown to be limited by the onset of thermally induced phase mismatching. Peak uv power can be increased to 85 mW by chopping the radiation from the pumping laser.