Soft-landing

Figure 9.7 Temperature-programmed reaction (TPR) spectra for CO oxidation at a series of model catalysts prepared by the soft landing of mass-selected Aun and AunSr cluster ions on MgO(lOO) thin films which are vacancy free (typically 1 % of a monolayer), (a) MgO (b) Au3Sr (c) Au4 (d) Au8. Also shown is the chemical reactivity R of pure Aun and AunSr clusters with 1 < n < 9. (Reproduced from Ref. 21).

The deposition of mass and charge selected ions onto surfaces is underway but is in its infancy. How do the ions survive the collision with a surface This question has a myriad of answers depending on many variables and will have a future in investigative studies. A soft landing is now a possibility (280) and allows the potential spectroscopic investigation of trapped ions. So far no transition metal ions have been examined using this method but it is only a matter of time. Soft landings via inert gas matrices also have potential in the surface deposition of mass selected clusters. 

Preparing protein microarrays by soft-landing of mass-selected ions. Science 1351. ... 

Parsons et al(Ref 83a) applied gas chromatography to separation of MNT and DNT isomers from their mixts. Ettre Varadi(Ref 85) used it in analysis of thermal degradation products of polymers, such as NC. Kuwada (Ref 89) detd w in hydrazine and de la Porte Lightenberg (Ref 100) detd triacetin in NG propint. Wilhite(Ref 100a) designed a gas chromatograph intended to be soft-landed on the surface of the moon as part of the "Surveyor spacecraft. It is assumed that the gas chromatograph would conduct, while on the lunar surface, an analysis of volatile constituents found on the moon... 

The structures for small Si clusters were verified in several experiments. Small clusters can be soft-landed on an inert gas matrix, permitting Raman4 or IR5 spectroscopy. This confirmed the Sin geometries for n < 7. Further proof came from vibrationally resolved photoelectron spectroscopy (PES),6 which exposed some normal modes of anions as overtones on the photoelectron spectra. The electronic transitions also contain structural information about anions.7 PES established a major difference between Sig and Si6, revealing the charge-dependence of Si cluster geometries (Fig. 2).7... 

S.C. Nanita et al., Chiral enrichment of serine via formation, dissociation and soft-landing of octameric cluster ions. J. Am. Soc. Mass Spectrom. 15, 1360-1365 (2004)... 

Future spacecraft missions to solar system objects are primarily being oriented towards remote-sensing experiments, in contrast to the soft-landed in situ experiments and sample-return initiatives during the 1970 s and 1980 s. Because reflectance spectroscopy has become one of the most important investigative techniques in the planetary sciences, current and planned space missions for the 1990 s and 21st century should include visible and near-infrared spectrometers in their instrument payloads. Reflectance spectral measurements from space would provide more favourable viewing geometries, eliminate problems due to telluric water and C02, and improve the resolution of areas scanned on a nearby planetary surface. 

Still most dynamical simulations of reactions at surfaces are limited to rather simple systems, such as the adsorption of diatomic molecules on low-index single crystal surfaces. With the development of more efficient algorithms and the improvement of computer power, more and more complex systems will be able to be addressed. One recent example is the ab initio molecular dynamics simulation of the soft-landing of Pd clusters on oxide surfaces [127] where up to n = 13 Pd atoms have been taken into account in the calculations. 

European Plastics News 30, No.3, April 2003, p.18 SOFT LANDING Reade L... 

In order to characterize the MgO sites where the Pd atoms are stabilized after deposition by soft-landing techniques, we used CO as a probe molecule [61]. The adsorption energy, Eb, of CO has been computed and compared with results form thermal desorption spectroscopy (TDS). The vibrational modes, (o, of the adsorbed CO molecules have been determined and compared with Fourier transform infrared (FTTR) spectra. From this comparison one can propose a more realistic hypothesis on the MgO defect sites where the Pd atoms are adsorbed. 

Aug. 17, 1970 Venera 7, lander Dec. 15, 1970, first soft landing on Venus, measured atmospheric composition, pressure, and temperature, survived 23 min (Marov, 1972)... 

Fig. 16.2 A schematic of the soft-landing technique where Au clusters are deposited onto the Xe buffer layer which rests above a thin metal oxide film...

Harbich W (1999) Soft landing of size-selected clusters in chemically inert substrates. Phil Mag B 79 1307... 

Bromann K, Brune H, Felix C, Harbich W, Monot R, Buttet J, Kern K (1997) Hard and soft landing of mass selected Ag clusters on Pt(lll). Surf Sci 377 1051-1055... 

Another way to prepare model catalysts (under UHV conditions) is to grow the clusters in gas phase and depose them on the substrate. However, to avoid implantation, fragmentation, and dynamic coalescence, it is necessary to soft-land the clusters. A first possibility is to decrease the kinetic energy of the clusters to less... 

Figure 14 CO oxidation on size-selected Pt clusters soft-landed on MgO. CO2 production per Pt atom as a function of n. (From U. Heiz et al. [41].)...

At this moment, the BREEZE Project cannot be economically survive in Japan, because of surprisingly low price of petroleum, though it may survive in some part of Asian countries. But, we will never be able to receive benefits from low price of oil so long time. And we have almost no petroleum or natural gas resources in Japan. I believe, especially in this country, we should prepare for post petroleum era and think of the way for soft-landing to another new industrial or social system. I believe that will be biological recycling system. The BREEZE Project is the pioneer of the new system in the new era. 

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