Optical triggers

Burnham, K. S. Schuster, G. B. A search for chiral photochromic optical triggers for liquid crystals photoracemization of l,l -binaphthylpyran through a transient biaryl quinone methide intermediate. J. Am. Chem. Soc. 1998, 120, 12619-12625. 

Chain C-K, Hofrichter J, Eaton WA. Optical triggers of protein folding. Science 1996 274 628-9. 

Traditionally, x-ray spectroscopy measures an inhomogeneous distribution of structures, represented by the nuclear Debye Waller factors, and yields no information on the time scales of their rearrangements. Collective protein motions after fast optical triggers, on the other hand, have been studied with the help of pulsed synchrotron radiation with nanosecond time resolution (11). (See also Ref. 12 for a collection of review articles on time-resolved diffraction techniques.)... 

Keywords. Type-II, Interband Tunneling, Optical Triggering, Terahertz oscillator. 

D. Woolard, W. Zhang, E. Brown, B. Gelmont and R. Trew, An optically triggered I-RTD hybrid device for continuous-wave generation of THz oscillations. Pro. of SPIE Terahertz for Military and security Applications IV, 6212 May 5,2006. 

Photoacids as Ultrafast Optical Triggers for Proton Transfer... 

Figure 12. Overview of envisioned thermoopticaUy programmable materials. Left image shows experimental arrangement and process by which optically triggered spatial distributions in gellation (and hence material properties) occur. Right image shows 3D overview of technique.

In Fig. 13.18, the normalized eurrent ratio of Brij 56-templated TSUA-modified nanocomposite films is 40%. However, in another experiment using P123-templated films that have a larger pore size (ca. 6.5 nm), the normalized current ratio is only 1.2%. Because the molecular length of azobenzene ligands located on the pore surfaces is 1.8 and 1.5 nm in the trans and cis forms, respectively, the optically triggered restriction in pore size is expected to have a diminished effect on transport for P123-templated films compared with the smaller pore size Brij 56-templated films. 

Optically triggered molecular switches are a potential way of triggering optical signals. A simple photochromic process that has been extensively used in the design of molecular switches uses the dithienylcyclopentene group as the molecular switch, for example, 5.15. This class of compound can undergo a reversible... 

A more complicated optically triggered molecular switch based on spiropyran (5.16) responds to chemical and optical inputs and produces an optical output (Scheme 5.3). Colourless spiropyran (5.16a) does not show any absorption at wavelengths greater than 400 nm. It switches to a purple merocyanine chro-mophore (5.16b, = 563 nm) upon irradiation with UV light. The merocyanine... 

In these cases, no transients assignable to biaryl quinone methides were observable by LFP, although Burnham and Schuster have assigned a 560-nm (x = 5 0,s in cyclohexane) transient to the corresponding binaphthyl quinone methide. The photoreversible nature of these reactions (they are photochromic) prompted Burnham and Schuster to investigate the binaphthyl system (Eq. (39.26)) as a possible chiral photochromic optical trigger for Hquid crystals ... 

Sub-Millisecond Thermally Isomerizing Azophenols for Optically Triggered Oscillating Materials... 

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