George G. Teather

Pulse radiolysis studies of time dependent spectral shifts of the solvated electron in ethanol and deuterated ethanol glasses at 76 K

The initial (?200 nsec) spectra of the trapped electron are similar in C2H5OH, C2H5OD, C2D5OH, and C2D5OD glasses at 76 K with λmax ∼1300 nm. The kinetics of the spectral shifts to the stable values of λmax near 540 nm are similar for C2H5OH and C2H5OD and resemble the kinetics of a series of first order processes or of tunneling reactions. Structure seems to be present in the partially relaxed spectra and may result from specific geoemetrical orientations of first solvation shell molecules.

Optical Measurements on Solvated Electrons in Pulse-Irradiated Liquid Propane,

Abstract A broad absorption spectrum with λ max ⩾ 2000 nm has been observed in pulse-irradiated liquid propane at low temperatures, and assigned to the solvated electron. The electron decays by geminate recombination with an initial half-life of ⩽ 95 nsec at −185°C.

Positive ions in alkane and mixed alkane glasses

Alkane and mixed alkane glasses have been studied by pulse radiolysis. The spectrum for squalane (SQ) was found to be made up of contributions from both the trapped electron and the primary positive ion of squalane (SQ/sup +/). Charge transfer between the solvent positive ion and solute has been directly observed for the first time in mixed alkane glasses. In an N/sub 2/O-bubbled 3-methyloctane (3MO) glass containing 1 vol % SQ, adsorption due to SQ/sup +/ was seen to grow, concomitant with the decay of 3MO/sup +/. Growth of SQ/sup +/ was also observed in an N/sub 2/O-saturated glass of 3-methylpentane containing 2 vol % SQ.

The effect of accumulated dose at 6 and 72 K on electron trapping in ethylene glycol-water glass

Abstract In the pulse radiolysis of ethylene glycol-D 2 O glass at 6 K, G (e - IR ) ⋍ 4.9 and G (e - vis )⋍0.3; by contrast pulse radiolysis of pure ethylene glycol glass at 6 K gives very little IR absorption. The effect of previous irradiation at 6 or 72 K on the ethylene glycol-D 2 O glass is to modestly reduce initial yields at 6 K. The results of the pulse experiments do not substantiate a previous report that shallow traps are efficiently consumed during irradiation at 77 K.

Two fast photodiodes for use in pulse radiolysis

Abstract In this paper we describe the characteristics of two photodiodes which make them very useful for pulse radiolysis studies. These detectors are the EG & G SHS-100 Si photodiode and the Barnes room temperature A-100 InAs photodiode. The former has a linear output up to at least 6·5 mA, has a 0–98% response time ≌ 15 ns and is distinguished from Si photodiodes previously described by having no detectable slow component to its response. The 0–98% response time of the A-100 photodiode and the circuit developed for it is about 60 ns, and it also shows no detectable slow response component. The output of the A-100 is linear up to at least 2 mA, and we have used it for absorption measurements between 450 and 3200 nm.

Performance measurement, management and reporting for S&T organizations—An overview

An integrated approach to performance measurement, management and reporting is presented which builds on the well known logic diagram approach of evaluation theory. The addition of explicit consideration of reach, defined as clients, co-delivery partners and stakeholders, supports a more holistic, balanced approach to the concept of performance, which has found acceptance among S&T performers and central agencies in Canada and the U.S. The description of the “performance framework approach” is supported by rationale for its use at both operational and strategic levels of S&T management. Also included are discussions of recent complementary work and examples of successful use of the approach.

Pulse radiolysis of crystalline D2O at 6 K

In experiments on the pulse radiolysis of crystalline D2O ice at a nominal temperature of 6 K, yields of e−vis, e−ir and the OD radical have been measured as a function of accumulated dose. The yield of e−ir shows a large effect of dose, increasing from Ge=1.03×104 (G≂0.27) for a previously unirradiated crystal to Ge=4.1×104 (G≂1.08) for a sample that had received 300 krad. The effect of dose is decreased to about half by annealing at 12.5 K, but can only be completely eliminated by annealing above 100 K. The effect is interpreted as being due to the scavenging, by D and OD, of D2O+ which otherwise recombines with e−qf. The G of OD at 6 K for a previously unirradiated crystal was measured as 3.8; this is much higher than the previously reported G of OH from γ‐irradiated H2O ice at 4 K.

Computer-based data acquisition system for pulse radiolysis studies

Abstract A computer-based system for the study of transient light absorption is described. It automatically subtracts and measures the quiescent light level, digitizes and stores the transient absorption, and monitors the absorption at a reference wavelength. Absorptions as small as 0.1°, in a time domain from a few nanoseconds to several hundred microseconds can be studied, and measurements of both reaction kinetics and absorption spectra are simplified by the use of the system. The system has been developed using commercially available electronic modules and integrated circuits, and is supported by an extensive software package.

Measurements of temperature changes during pulse radiolysis at 6 K

Abstract At 6 K, the temperature of a pulse radiolysis sample rises noticeably due to the absorption of energy from the radiation pulse and the analyzing light. This temperature rise was measured by means of a chromel/gold-iron thermocouple imbedded in the centre glassy samples of glycerol, 3-methylpentane and ethylene glycol/D2O. The technique was verified by using glycerol, for which the specific heat at these low temperatures is known, to compare the experimentally measured temperature rise due to a radiation pulse to the calculated rise. The temperature of a sample of 3-methylpentane was found to rise from 6 to 9.5 K due to a 6 krad radiation pulse. The temperature rise due to the analyzing light can be minimized by the use of a fast shutter and filters.

Evaluation and management of multi-departmental (horizontal) science and technology programs

In Canada, there has been a recent increase in the number of horizontal or multi-departmental programs with higher level objectives beyond the mandate of any one department. These programs are designed to take advantage of the capabilities of several organizations to address major national policy objectives. Two examples of horizontal programs are discussed, with differing degrees of cooperation and interaction among the participating departments. Management of these initiatives requires the participating organizations to work cooperatively, an approach that is contrary to the culture of many organizations. Evaluation of multi-departmental programs requires greater attention to early outcomes associated with smooth functioning of the relationships between the participating organizations and with stakeholders as a necessary requirement for program effectiveness and achievement of objectives. Copyright , Beech Tree Publishing.