TL Analysis Research Articles

Carrier Traps in Polyethylene Naphthalate (PEN): Photoelectret

Electronic carrier traps in polyethylene naphthalate (PEN) were investigated by TSC and TL analysis in the temperature range from -196°C to 160°C. Two broad peaks were observed in the TSC and TL from PEN films illuminated with light of wavelength 360 nm at -196°C. The detrapping process was closely related to the molecular motions, the so-called γ and β relaxations. The apparent trap depths ranged from 0.1–0.5 eV.

Activation of Tl, Pb and Bi by 10–160 MeV neutrons: Possible application to the analysis of Bi+

The medium energy intense neutrons (MEIN) available at the Brookhaven Chemistry Linac Irradiation Facility have an energy distribution up to ∼160 MeV an effective neutron flux of ∼1.3×1011 cm−2s−1. The present work explores the feasibility of using this facility for the analysis of Tl, Pb and Bi by activation with MEIN. The most sensitive reactions, from a practical standpoint, were found to be Tl (n, xn)200Tl (x=4, 6), Pb (n, xn)204mPb (x=0, 3, 4. 5) and209Bi (n, 6n)204Bi. The absolute sensitivities attainable with these reactions are 0.1, 0.05 and 0.08 μg of Tl, Pb and Bi respectively, for 1 h irradiation at 1.3×1011 n cm−2s−1 with samples counted 2 h after the end of irradiation. The advantages of the method over thermal neutron activation analysis are that all three elements can be assayed at the sub-microgram concentration levels by γ-spectrometry with the help of a simple radiochemical purification and the analytical results can be verified by cross checking via the multiple (n, xn) reaction products. However, interference from Bi in the determination of Pb and from Pb and Bi in the determination of Tl limits its usefulness to the analysis of Bi.

Chemical studies of L-chondrites—I. A study of possible chemical sub-groups

Radiochemical neutron activation analysis of Ag, As, Au, Bi, Co, Cs, Ga, In, Rb, Sb, Te, Tl and Zn and major element data in 14 L4-6 and 3 LL5 chondrites indicates that the L-group is unusually variable and may represent at least 2 sub-groups differing in formation history. Chemical trends in the S/Fe-rich sub-group support textural evidence indicating late loss of a shock-formed Fe-Ni-S melt; the S/Fe-poor sub-group seemingly reflects nebular fractionation only. Highly mobile In and Zn apparently reflect shock-induced loss from L-chondrites. Data for L5 chondrites suggest higher formation temperatures and/or degrees of shock than for LL5 chondrites.

Thermoluminescence authenticity testing of ancient ceramics using radiation-sensitivity changes in quartz

Routine use of this new TL dating principle gives support to authenticity judgements made using the standard high temperature TL analysis [15, 16]. In the course of over 300 investigations (in addition to those described here) made at the Research Laboratory for Archaeology and History of Art, Oxford, at no time have the two TL methods appeared to be in conflict. In the broader field of archaeological dating it is anticipated that age determination will be possible for Mediaeval (and younger) pottery with an accuracy competitive with that possible by the radiocarbon method for such recent material [17].

The hyperfine structure of Tl II

In a previous publication a term and a hyperfine structure analysis of the spark spectrum of thallium, Tl II, were presented. The hyperfine structure analysis, although limited by the low resolution of the spectrographs employed, confirmed the intensity rules and the vector relation for the compounding of I and J; showed for the electronic configurations involving a 6 s electron that the energy of interaction between I and J was large; and established I = ½ for thallium. In view of the recent development of the theory of hyperfine structure, more accurate detail is desirable for the verification and the extension of this theory. The consistent interpretation of the preliminary hyperfine structure analysis, the completeness of the term analysis, the magnitude of the hyperfine separations, and the simplicity of the patterns, features of Tl II, suggested that for this spectrum a detailed hyperfine structure analysis, sufficiently accurate to confirm or show the limitations of the theory, would be feasible. Accordingly, the hyperfine structure of Tl II was investigated. The details and results of this investigation are presented below. The spectrum of thallium was excited by two methods: In the first, a condensed discharge was produced in thallium vapour, contained in a quartz discharge tube, by connecting the two terminals, sealed into the tube, in parallel with a condenser, and in series with an adjustable spark gap and the secondary of a transformer; in the second method, an electrodeless discharge was produced in the vapour by passing a high frequency current, generated in an oscillating circuit by a transformer with its secondary in series with a capacity and in parallel with a spark gap, through a heavy copper wire coiled around the tube containing the vapour. Both methods gave satisfactory excitation, but as the electrodeless method was more easily controlled it only was used in the latter part of the investigation. The radiation, excited by these methods was photographed in the spectral region λλ 7100-2300 A. U. in several orders, from the first to the fourth depending on wave-length, of a 3 metre concave grating of 60,000 lines, ruled with 15,000 lines to the inch. From the spectrograms obtained, the separations and the relative intensities of the hyperfine structure components were determined for the lines of appreci­able intensity in the analysis of Tl II, as presented by McLennan, McLay and Crawford and extended by Smith; and for a few additional lines classified in this investigation, the classification of which involved a slight modification and extension of the former term analysis.