Spectroscopy retrospective

K. Siegbahn Photoelectron spectroscopy retrospects and prospects. Phil. Trans. Roy. Soc. Lond. A 318, 3 (1986)... 

Moskovits, M., Surface enhanced Raman spectroscopy a brief retrospective, J. Raman Spec trosc. 2005, 36, 485 496... 

In the mid-1980s, virtually simultaneous reports on two new precise molecular level constructions of sub-nanoscopic/nanoscopic size appeared in the literature. In 1984 we (DAT) reported the synthesis, isolation and characterization of the first iterated series of Starburst/cascade dendrimers based on genealogical synthesis [2, 77-83]. The following year Smalley, Curl and Kroto described the first observation of a 60-carbon fullerene by mass spectroscopy [43a]. More recently the synthesis of buckminsterfullerene has been achieved by physicists at the Max Planck Institute in Heidelberg [44] to give macroscopic quantities of the third allotropic and first molecular form of carbon, named after Buckminster Fuller. Similarities between these two constructions were not initially apparent, but in retrospect they deserve comment in so far as they each involve molecular level synthesis leading to closed geometrical architecture". 

The nature and breadth of the physical techniques used to investigate solid catalysts continue to increase rapidly in complexity. This statement pertains specifically to Mossbauer spectroscopy, which was applied to the characterization of solid catalysts as early as 1971 (7). A retrospective analysis of the use of Mossbauer spectroscopy in catalysis showed that it has consistently accounted for 3-10% of the communications presented at the International Congresses on Catalysis (ICQ (7%t at the ICC in Paris in 2004). Such continuity over the years reflects the high value of this technique in catalyst characterization. 

Jeanmaire DL, Van Duyne RP (1977) Surface Raman spectroelectrochemistry 1. Heterocyclic, aromatic, and aliphatic-amines adsorbed on anodized silver electrode. J Electroanal Chem 84 1-20 Moskovits M (2005) Surface-enhanced Raman spectroscopy a brief retrospective. J Raman Spectrosc 36 485 96... 

The approach by Dautzenberg et al. emphasizes in our opinion a valid and hitherto hardly exploited inroad to the FT kinetics. In retrospect, with the knowledge now available from surface spectroscopy, an experimental verification of the complicating factors mentioned appears desirable. This would be valuable in particular because the main conclusion, viz. a high coverage of steady-state catalysts with growing chains, has not been confirmed by the in. situ IR studies, discussed in the next section. 

Conclusions from the Case Study. Exercises such as these are quite common in the characterization of complex solids and do indeed require the combined expertise of a group of specialists. The set of techniques required varies from case to case, but the more or less standard combination of two or more complementary techniques as part of the arsenal is very useful. In retrospect, we were able to identify the techniques which were crucial to solving this problem XPS/TEM, LEIS, XRD and EXAFS. A number of others (Magic-Angle-Spinning NMR (MAS-NMR), Raman Spectroscopy and FTIR (Fourier Transform Infrared Spectroscopy) were applied, but did not add significantly to the final result. The study of various samples which were synthesized in different ways and which showed different catalytic activities did prove relevant, but is not described in detail here. 

The interpretation used to explain the absorption spectra of Tl(l) and Pb(ll) solid-state complexes can also be extended to aqueous solution spectra of Pb(ll) complexes (Fig. 5) (54—60, 62). Although aqueous lead halide absorption spectra reported by Fromherz et al. (54, 55) were not originally interpreted in the context of CT spectroscopy (56, 125), in retrospect it is clear that the bands reported are the same as those observed in doped alkali halide crystals, as are later spectra reported by Bendiab et al. (59, 60). For example, in solution a spectral shift to longer wavelengths is observed for increasing atomic number of the halogen ligand (54, 55), which is consistent with a CT process (126). 

The steps and missteps in the process of discovering new elements led to caution in accepting a previously unidentified spectroscopic feature as evidence for a new element (Boyd 1959). Chemical characterization was required. For example, masurium was proposed for element 43, and illium and fiorentium were proposed for element 61 based on atomic spectroscopy of extracts from minerals. In retrospect, it is clear that there was evidence for unusual conditions for these elements. For example, above 7N the only mass numbers of stable isotopes of elements with odd atomic number are also odd, and there is only one stable isobar for each odd A. Molybdenum (Mo) has stable isotopes 92, 94—98, and 100. Ruthenium has 96, 98-102, and 104. Niobium has 93, and rhodium 103. Nothing is left for technetium, which would have the best chance for stability at mass numbers 97 and 99. Similarly, either neodymium or samarium has a 3-stable isotope fi om 142 to 150 nothing is left for promethium. 

Molecular Spectroscopy at Low Temperatures A High Resolution Infrared Retrospective... 

Principles and Characteristics A wide variety of structural analysis tools is available employing X-rays (Table 5.59). Micro-focused X-ray sources allow small area spectroscopy, quantitative line scans and retrospective chemical state imaging based on high energy resolution spectra from user-defined areas. X-ray imaging complements electron imaging allowing to study relatively thick samples. 

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