Solvated and Stabilized Electrons in Radiation‐Chemical Processes

Abstract

ConclusionsMethylation analyses of polysaccharidea from wood [35,361, fungi [30,31,37-401, lichens [411, and bacteria 13*.34,421 have recently been performed in the authors' laboratory using the Hakomori procedure for methylation and GLC-mass spectrometry for the qualitative and quantitative analysis of the methylated sugars. This technique has the following advantages:1. It is more accurate and sensitive than previous procedures. It is thus possible to identify and determine the relative proportions of minor components, which may be structurally significant. The electrons solvated in metal-ammonia solutions are relatively stable; by contrast, hydrated electrons are very unstable and have been discovered only recently during radiolysis of water. They can be regarded as the simplest radicals, Radiation chemical production of solvated electrons has proved to be a particularly elegant method for the qualitative and quantitative investigation of the reactions between these electrons and numerous compounds, whose rates are partly controlled by diffusion. It has been possible in some cases to identgy optically and ESR-spectroscopically the resulting short-lived products (radical-anions). The similarity between the physical and chemical properties of electrons solvated in solutions and those of electrons stabilized in the solid phasesuggests that the two species are identical. . tionsC31, known for the past hundred years o r so. Several indirect proofs for the existence of hydrated electrons were published in the following yearsC4-71. The first direct proof was obtained in 1962 when a n intense blue color was observed after the irradiation of glasses formed by NaOH solutions[8,91, and whenshortly [4] E. Hayon and J .

Postirradiation Electron Transfer vs Differential Radical Decay in X-Irradiated DNA and Its Mixtures with Additives. Electron Spin Resonance Spectroscopy in LiBr Glass at Low Temperatures

“…Therefore, not considered before in the literature, it appears likely that there must be species in the glass which can destroy free radicals with time at 77 K and which are indeed ESR-mute as discussed above. A prominent example for an ESR-mute species is the solvated electron in ice at neutral pH and at 77 K. Only at alkaline pH a sufficiently deep trap structure appears to have evolved allowing for the species to become ESR visible. , A similar situation might apply to the matrix defects discussed here.…”

Radical Photochemistry in Oxygen‐Loaded Ices

“…[17,20] In these studies the chemical analysis was not complete-in particular, the atomic oxygen and the HO 2 C radicals were not detected. In earlier studies Taub and Eiben [21] used electron spin resonance spectroscopy to follow the production of OHC and HO 2 C as radiolytic products from crystalline ice irradiated with high energy electrons. However the radicals were observed at temperatures up to 0 8C, which is in contradiction with many recent studies, and requires reconsideration of their identification.…”

“…The fact that peak 3 increases in intensity in 10 3 , and H 2 O 2 ), but not the HO 2 C radical. We therefore assign peak 3 to HO 2 C. HO 2 C, an expected product from the radiolysis of pure water ice, [15,16,19,21] is also observed in Figure 3 trace d. Peak 3 is less intense in the 50:50 O 2 /H 2 O mixture than in the 10:90 O 2 /H 2 O mixture; this observation is explained by the decrease in H and OHC availability as the water content decreases, as discussed below. Similar to the OHC transition, peak 3 corresponds to the less energetic excitation, for example, from the inner shell (O1s) to the low-lying orbital (that is, the half-occupied p orbital).…”

Structural Control in the γ-Radiation-Initiated Polymerization of 1-Vinyluracil

“…The value of Mc at this concentration is 88,000.18 Two other polymers were used at a volume fraction of 0.26 where Mc will be 54,000; their molecular weights were ~74,000 and ~110,000. These two polymers gave 13-fold and 15-fold changes in viscosity, respectively, between the isoprene-capped and terminated polymers, whereas the first two gave 10-fold increases. Clearly, although the latter two experiments were dismissed as being caused by experimental error, what was really observed was an increase in the viscosity ratio as conditions approached the region of validity of the 3.4-power law.…”