Coherent chemistry

Shapiro M and Brumer P 1989 Coherent chemistry—Controlling chemical reactions with lasers Acc. Chem. Res. 22 407... 

Seideman T, Shapiro M and Brumer P 1989 Coherence chemistry—controlling chemical reactions with lasers Chem. Phys. 90 7132... 

Other Excitation Schemes Phase-Coherent Chemistry... 

In recent years the theory of coherent chemistry has shifted towards attempts to actively control molecular dynamics rather than just to observe passively these ultrafast phenomena. These studies have created huge interest and much activity in the optical and chemical communities [426-428]. The first promising experiments have confirmed the fascinating theoretical predictions (see in [428]). 

Further advances in the field of coherent chemistry will require improved time resolution and tunability of the laser sources in the experiments [434]. Shorter laser pulses with a pulse duration of less than 20 fs will be appropriate. The optimum control technique will be achieved by specially tailored femtosecond pulse shapes [435-439], determined by sophisticated calculations using the theories of coherent chemistry [440-444]. Finally, more elaborate polarization and multipulse excitation schemes, including chirped and ultra-short pulses, will be needed. 

Normally, only the frequency and the intensity of a light field are considered in the interaction of radiation with matter. With the availability of short-pulse radiation with well-defined phase properties it has become possible to interact coherently with matter, opening up new possibilities of controlling chemical reactions and light-matter interactions. We will here consider two aspects of this quickly evolving field coherent chemistry and interference effects profoundly changing the absorptive properties of matter. 

Coherent Chemistry. Short-pulse laser radiation normally leads to broad and rather unspecific excitation of vibrational modes (See also Sect. 10.4). By tailoring the pulses, which typically would have a pulse length of 100 fe, by sending them into a pulse shaper, certain modes can be enhanced and others be suppressed. In particular, discrimination between chiral molecules (right- or left-handed) otherwise performing in an identical way could be considered, A pulse shaper is a stretcher-like arrangement (Sect. 8.7.2) with... 

Modem photochemistry (IR, UV or VIS) is induced by coherent or incoherent radiative excitation processes [4, 5, 6 and 7]. The first step within a photochemical process is of course a preparation step within our conceptual framework, in which time-dependent states are generated that possibly show IVR. In an ideal scenario, energy from a laser would be deposited in a spatially localized, large amplitude vibrational motion of the reacting molecular system, which would then possibly lead to the cleavage of selected chemical bonds. This is basically the central idea behind the concepts for a mode selective chemistry , introduced in the late 1970s [127], and has continuously received much attention [10, 117. 122. 128. 129. 130. 131. 132. 133. 134... 

Hepburn J W 1995 Generation of coherent vacuum ultraviolet radiation applications to high-resolution photoionization and photoelectron spectroscopy Laser Techniques in Chemistry vol 23, ed A B Myers and T R Rizzo (New York Wley) pp 149-83... 

As a result of the systematic application of coordination-chemistry principles, dozens of previously unsuspected stnicture types have been synthesized in which polyhedral boranes or their anions can be considered to act as ligands which donate electron density to metal centres, thereby forming novel metallaboranc elusters, ". Some 40 metals have been found to act as acceptors in this way (see also p. 178). The ideas have been particularly helpful m emphasizing the close interconnection between several previously separated branches of chemistry, notably boron hydride clu.ster chemistry, metallaboranc and metallacarbaborane chemistry (pp. 189-95). organometallic chemistry and metal-metal cluster chemistry. All are now seen to be parts of a coherent whole. 

A useful theme for cohering much of the chemistry of compounds containing the CN group is the concept of pseudohalogens, a term introduced in 1925 for certain strongly bound, univalent radicals such as CN, OCN, SCN, SeCN, (and N3, etc.). These groups can form anions X , hydracids HX, and sometimes neutral species X2. 

Panel). Most of the basic processes were established almost a century and a half ago, but a coherent theoretical explanation was not available until the publication in 1938 of the classic paper by R, W. Gurney and N. F. Mott. (Pwc. Roy. Soc. A164, 151-67 (1938)). Since then the subject has stimulated a vast amount of fundamental research in wide areas of solid-state chemistry and physics. 

The first time I recall being clearly directed to the periodic table and some of its features, was on making the transition between Ordinary Level and Advanced Level chemistry at age 16. This delay added to the delight of the discovery, if anything, since I experienced the wonder of seeing how previously covered information suddenly fell into place in a coherent framework. 

Develop and legitimise a new curriculum emphasis for school chemistry, in terms of a new coherent combination of a substantive, philosophical and pedagogical substmcture. 

What is the content and focns of a new vision on the chemistry edncation cnr-ricnlnm in terms of the three coherent snbstractnres discnssed above that shonld lead to meaningful learning of micro-macro thinking ... 

The successful chairmanship and the apparent qualities of personnel management landed several offers of deanships in Yngve s lap. He decided, to my delight, to remain a dedicated scientist. Administrative obligations remained, he assumed the role of Director of the Quantum Theory Project in 1983 and led this rather informal association of faculty members from Chemistry and Physics to be established, in 1987, as the "Institute for Theory and Computation in Molecular and Materials Sciences" with a well defined position in the University system. This was another demonstration of the ability to create coherence and commitment amongst a body of strong minded people with diverse interests. It is a consequence that Florida remains a world renowned hub of quantum chemistry activities. 

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