Photoelectron spectroscopy detection-observation

Fleisch et al. (1984) employed x-ray photoelectron spectroscopy (XPS) on spent residuum HDS catalyst and also found the V2S3 sulfide phase. In addition, the XPS technique enabled the identification of Ni forms. Only sulfides in either the Ni3S2 or Ni2S forms were observed. Nickel metal and NiS were not detected. 

More recently, Muchall and Rademacher <1998JST(471)189> have carried out thermolysis of 3,6-dimethyl-, diethyl-, and dipropyl-substituted l,2,3,6-tetrahydro-l,2,4,5-tetrazine to yield the corresponding N-substituted imi-nes 43a-c (Scheme 1). They utilized photoelectron spectroscopy to detect the intermediates and the products formed. Thus, PS of tetrahydrotetrazines shows no change up to 400 °C but at 450 °C thermolysis takes place and the bands belonging to ethanimine and nitrogen appear. The ionization potential observed is shown in Table 4. 

A number of photoelectron spectroscopy studies of organophosphorus compounds have been reported. ESCA spectroscopy may be used to detect changes in gross structure but does not appear to be suitable for studying fine stereochemical aspects such as differentiating between the cis- and trans-isomers of (148). Similar limitations were observed for the inner-... 

Pichot et al. (2001) conducted a preliminary study of irradiation effects on thorium phosphate-diphosphate. Powdered samples were irradiated with 1.5 Gy dose of gamma-rays. The formation of PO b and POO free radicals were detected using electron spin resonance (ESR) and thermoluminescence (TL) methods. These free radicals do not modify the macroscopic properties of the TPD and disappear when the sample is heated at 400°C. The implantation of 1.6 MeV He with a fluence of 10 ions/cm and 5 meV Au with a fluence 4 x 10 ions/cm causes some surface damage to sintered samples. Amorphization and chemical decomposition of the matrix were observed for the dose of 10 ions/cm and higher when irradiated with Pb (200 keV) and Au " (5 MeV). These effects were evidenced by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). 

Erlandsson et al. [42] reported the most detailed study of the stability of electrochemically prepared polypyrrole containing Bp4 who used x-ray photoelectron spectroscopy to study the reactions of polypyrrole, exposed to various atmospheres at room temperature. They observed electrical conductivity decay on exposure to various atmospheres in the order of O2 -1- H2O 5- O2 > Atm. > At and Ar -L H2O over a period of 500 hours as shown in Figure 16.16. Exposure to dry air or oxygen produced a measurable electrical conductivity decay by a factor of two over 500 hours. Water and oxygen had the most significant synergic effect where the electrical conductivity decreased by a factor of 7 over the same period. XPS studies showed that the concentration of the counter-ion decreased on storage in all cases and the formation of BF3 and HF could be detected in mass spectroscopic studies at elevated temperatures. They found little correlation between loss of BF " ions with the loss of electrical conductivity. 

More recently, substituted transient thioxosilanes have been obtained by a retro-ene reaction according to Scheme 6.3. In this study, the thermolysis of several thiosilanes such as 9a and 9b (Scheme 6.3) was examined using both high-resolution mass spectrometry (HRMS) and photoelectron spectroscopy (PES). While monomeric (/-Pr)2Si=S (10b) was obtained from 9b and identified independently by both methods employed, 10a was not observed in the mass spectrum of the thermolysis products of 9a. Moreover, the detection of monomeric 10a by its PE spectrum was hampered by strong bands due to allene and undecomposed precursor obscuring bands assumed to stem from lOa.PH... 

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