Laser ablation, molecular beam

In 2008, Alonso and coworkers reported a combined experimental and computational study of the conformations of cysteine. They located 11 low lying conformers at MP4/6-311-i i-G(d,p)//MP2/6-311-l-l-G(d,p), and the five lowest energy structures are shown in Table 3.15. Using laser ablation molecular beam Fourier transform microwave spectroscopy, they identified six conformers present in the gas phase. Comparing the computed rotational constants and nuclear quadrupole coupling tensor components with the experiment, they were able to decidedly match up all six experimental conformers with computed structures. Of the five low energy conformers listed in Table 3.15, four of them were identified in the experiment. 

Alonso et al. examined the glycine-one water complex using laser ablation molecular beam Fourier-transform microwave spectroscopy. By comparison of the observed rotational parameters and those predicted from an MP2/6-311+G(d,p) optimization, they concluded that the only observed isomer is that formed of the neutral isomer and water, 44a. Balabin examined the glycine-one water complex using IR spectroscopy. While he too found 44a, he was able to detect a small amount of 44b and 44c. An interesting side note is that anharmonic corrections were necessary in order to match up the computed (MP2) frequencies with the experimental values. These experiments indicate that more than one water molecule is needed to stabilize the zwitterion tautomer. 

Figure 5. A block diagram of the laser ablation, molecular beam spectrometer at the University of Waterloo. [Reprinted with permission from ref. 74. Copyright 1996 Academic Press.]...

The MgCH3 A2E-X2A1 spectrum was analyzed in a laser ablation molecular beam spectrometer [125]. It was noted in this article that the eaa... 

Surface catalysis routes using alkaline earth oxides have yielded mixtures of various (CO) n = 2-6 ) species from CO [91]. These routes are of mechanistic interest, but are of no synthetic value as only trace amounts of product are detected. Recent work has been reported that shows the formation of the rhodizonate mono-anion from the reaction of CO with molybdenum suboxide cluster anions Mo Oy" (y < 3x), which are generated using pulsed laser ablation/molecular beam methods [92]. The results suggest that a series of reactions occur involving the oxidation of CO until the oxygen content of the clusters is depleted, followed by metal carbonyl formation and, ultimately, free C Oe" formation. 

Smdies on techniques for thin film deposition divide these into two groups, depending on the nature of the deposition process. Physical methods include physical vapor deposition (PVD), laser ablation, molecular beam epitaxy and sputtering. Chemical methods comprise of gas phase and solution deposition. The gas phase techniques include chanical vapor deposition (CVD) and atomic layer epitaxy (ALE). Spray-pyrolysis deposition, sol-gel, spin-coating and dip-coating are techniques based on solution deposition. 

Due to the short coherent length of HTSCs, only smooth surfaces on structurally perfect layers allow these planar technologies. A number of modem deposition techniques (physical vapor deposition including sputtering, laser ablation, molecular beam epitaxy as well as metallorganic chemical vapor deposition etc. see, e.g., Becht 1996) result in high values of critical temperature and critical current. However compact single-crystalline... 

Lopez JC, Pena MI, Sanz ME, Alonso JL (2007) Probing thymine with laser ablation molecular beam Fourier transform microwave spectroscopy. J Chem Phys 2007 126... 

Laser-Ablation Molecular-Beam FomiCT Transform Microwave (LA-MB-FTMW)... 

Similar to 2DR, ribose (C5H5O5) is one of the most important monosaccharides since it constitutes a subunit of the backbone of RNA. NMR studies have shown that ribose in solution is a mixture of a- and p-pyranose and a- and p-furanose forms, the p-pyranose form being predominant. The recently settled crystal structures have shown that the a- and P-pyranose forms are present in the solid phase [239-243]. The structure in the gas phase has been experimentally investigated using a laser ablation molecular beam Fourier transform microwave spectroscopy (LA-MBFTMW) technique [62]. The high resolution rotational spectrum has provided structural information on a total of six rotamers of ribose, three belonging to the a-pyranose forms and other three to the P-pyranose forms. Recently, D-ribose (m.p. 95°C) has been submitted to a laser ablation broadband (CP-FTMW) spectroscopic study and eight conformers (two new a-pyranose forms) have been identified. A broadband section of the spectra is shown in Fig. 35 and the detected conformers depicted in Fig. 36. 

Lesarri, A., Mata, S., Lopez, J.C., and Alonso, J.L. (2003) A laser-ablation molecular-beam Fourier-transform microwave spectrometer the rotational spectrum of organic solids. Rev. Sd. Instrum., 74 (11), 4799-4804. 

The hybridizing component can also be formed directly on the surface of a pristine or modified nanocarbon using molecular precursors, such as organic monomers, metal salts or metal organic complexes. Depending on the desired compound, in situ deposition can be carried out either in solution, such as via direct network formation via in situ polymerization, chemical reduction, electro- or electroless deposition, and sol-gel processes, or from the gas phase using chemical deposition (i.e. CVD or ALD) or physical deposition (i.e. laser ablation, electron beam deposition, thermal evaporation, or sputtering). 

FIGURE 11.1 Top view of the crossed molecular beams machine. Shown are the main chamber, the primary (laser ablation configuration) and secondary source chambers, and the rotatable differentially pumped mass spectrometer detector. 

Motivated by the remarkable discovery of quasicrystalline ordering in solids in 1984 [1], wave propagation in deterministic non periodic media has been an area of intense research. Following the successful experimental realisation of a multitude of such structures through modem technologies, such as molecular beam epitaxy and laser ablation [2], their interest has increased ever since. The most widely known examples are quasi-periodic structures obtained by substitution rules, such as Fibonacci- or Thue-Morse-chains [3,4], Much less has been published on quasi-periodic chains constructed according to a Cantor-set algorithm, which are the subject of this note. 

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