Fast and ultrafast

A comprehensive review of fast and ultrafast time-resolved optical techniques. 

High flow-rate sampling at atmospheric pressure Fast and ultrafast GC-MS... 

Flash photolysis and laser flash photolysis are probably the most versatile of the methods in the above list they have been particularly useful in identifying very short-lived intermediates such as radicals, radical cations and anions, triplet states, carbenium ions and carbanions. They provide a wealth of structural, kinetic and thermodynamic information, and a simplified generic experimental arrangement of a system suitable for studying very fast and ultrafast processes is shown in Fig. 3.8. Examples of applications include the keton-isation of acetophenone enol in aqueous buffer solutions [35], kinetic and thermodynamic characterisation of the aminium radical cation and aminyl radical derived from N-phenyl-glycine [36] and phenylureas [37], and the first direct observation of a radical cation derived from an enol ether [38],... 

Fig. 3.8 Generic layout of a system suitable for studying very fast and ultrafast processes. Appropriate radiation sources may be a flash lamp, a laser or an electron accelerator, while optical, conductivity, or ESR detection systems may be employed.

The probe heads snpplied with modem solid-state NMR spectrometers vary in the diameters of the coils and, therefore, in the maximum MAS rate achievable. Recent developments in MAS technology led to the first conunercial nltra-fast MAS probe heads with MAS rate np to 65 kHz employing rotors with 1.2 nun diameter. When selecting an appropriate probe head, one should take into account the sensitivity of a nnclens under study. The faster the MAS rate, the smaller the amount of the sample reqnired. Typically, one employs MAS rates of 4 15 kHz. The lower end of these rates is covered by the probe heads with large MAS rotors (ca. 7 nun in diameter) snitable for nnclei with very low natural abundance and long relaxation times ( Si, N etc.). The fast and ultrafast MAS probe heads are particularly suitable for H and nnclei. 

In this book, we have made an effort to provide an overall view of the emerging trends in radiation chemistry authored by experts in the field. The introductory chapter covers the history of radiation chemistry, underlining its achievements and issues that need to be addressed in future research. By renewing its research directions and capabilities in recent years, radiation chemistry research is poised to thrive because of its critical importance to today s upcoming technologies. Detailed accounts of fast and ultrafast pulse radiolysis instrumentation development and recent advances on ultrafast... 

Pines, E., The Photoacidity of 1-Hydro-xypyrene from Forster Cycle to Marcus Theory, Summer School, Molecular Basis of Fast and Ultrafast Processes, Algarve (Portugal), June 12th-15th 2003. 

Grills, D. C. George, M. W. Fast and Ultrafast Time-resolved Mid-infrared Spectrometry using Lasers. In Handbook of Vibrational Spectroscopy, Chalmers, J. M., Griffiths, P. R., Eds. Wiley Chichester, UK, 2002 Vol. 1, pp... 

All these recent developments demonstrate that the fast and ultrafast absorption, fluorescence, and vibrational spectroscopies continue to evolve synergetically and at a rather rapid pace. It is our hope that even more progress in the instrumentation and its application in stilbene photophysics and photochemistry would follow in the coming years. 

Table 1 Comparison of calculated plate number, retention time, and peak-width at half-height using standard, fast, very fast, and ultrafast GC...

Harata A, Shen Q, and Sawada T (1999) Photo-thermal applications of lasers Study of fast and ultrafast photothermal phenomena at metal-liquid interfaces. Annual Review of Physical Chemistry 50 193-219. 

A powerful application of TRIR has been to use the z/(CO) and n(CN) vibrations of supramo-lecular coordination compounds to monitor electron- and energy-transfer processes in solution. For example, a combination of fast and ultrafast TRIR was used to show that excitation into the Re-MLCT transition of [(phen)(CO)3Re NC)Ru CN)(bpy)2] (phen= 1,10-phenanthroline) produces the Re-MLCT state, followed by energy transfer to the Ru-based MLCT state." For the related complex, (CO)5W(4,4 -bpy)W(CO)5 ns-TRIR was used to confirm that, on the IR... 

Due to the demand for faster GC separations in routine work in the eld of GC of essential oils, the development of fast and ultrafast GC seems worthy to be mentioned. The various approaches for fast GC have been reviewed in 1999 (Cramers et al., 1999). The most effective way to speed up GC separation without losing separation ef ciency is to use shorter columns with narrow inner diameter and thinner coatings, higher carrier gas ow rates, and accelerated temperature ramps. In Figure 2.1, the conventional and fast GC separation of lime oil is shown, indicating virtually the same separation ef ciency in the fast GC and a reduction in time from approximately 60 to 13 min (Mondello et al., 2000). 

Besides fast and ultrafast GC separations, one of the most important developments in GC has been the introduction of enantioselective capillary columns in the past with high separation efficiency, so that a great number of chiral substances including many essential oil constituents could be separated and identified. The different approaches of gas chromatographic separation of chiral compounds are briefly... 

In an effort to quantitate the increase in GCMS analysis speed, one author has suggested the descriptors fast, very fast, and ulfrafast (154). These are based on the definition of the new term, speed enhancement factor (SEF), which is defined as the product of column length reduction and the increase in carrier-gas Unear velocity for the chromatographic separation. Using this description, SEFs of 5-30, 30-400, and 400-4000 correspond to fast, very fast, and ultrafast. 

G. Ramakrishna, H. N. Ghosh, A. K. Singh, D. K. Palit, and J. P. Mittal, 2001. Dynamics of back-electron transfer processes of strongly coupled triphenyl methane dyes adsorbed on Ti02 nanoparticle surface as studied by fast and ultrafast visible spectroscopy. J. Phys. Chem. B 105, 12786-12796. 

Grills, D.C. and George, M.W. (2002) Fast and ultrafast time-resolved mid-infrared spectrometry using lasers. In Handbook of Vibrational Spectroscopy, Vol. 1 (eds J.M. Chalmers and P.R. Griffiths), John Wiley Sons, Ltd, Chichester, pp. 677-692. 

Table 1.1 Time scales for fast and ultrafast motions...

E. P. Gilbert, A. Lopez-Rubio and M. J. Gidley, Characterisation Techniques in Food Materials Science, in Food Material Science and Engineering, ed. B. Bhandari and Y. H. Rons, Wiley-Blackwell, Chichester, UK, 2012, p. 52. P. Giraudeau and S. Akoka, Fast and Ultrafast Quantitative 2D NMR Vital Tools for Efflcient Metabolomic Approaches, in Metabolomics Coming of Age with Its Technological Diversity, ed. D. Rolin, Advances in Botanical Research, Elsevier Ltd., 2013, vol. 67, p. 99. 

Nitz WR (2002) Fast and ultrafast non-echo-planar MR imaging techniques. Eur Radiol 12 2866-2882... 

A new field of chemistry was opened, namely the chemistry of labile particles atoms, free radicals, radical ions, carbenes, etc. The fest development of experimental techniques suitable for monitoring fast and ultrafast processes led to the study of mechanisms of energy exchange in collisions of particles and initiated the formation of nonstationary kinetics. 

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