Temperature tuning

Figure 12,19. Temperature tuning of an optical parametric oscillator. The continuous curve is a theoretical prediction and the circles represent measured data. (From Ref. 75.)...

The temperature tuning coefficient of TeOa is 0.025 nm/°C, so it is clear that in order to combat the effects of thermal heating of the crystal due to incident optical and aconstic power, as well as environmental considerations, a good level of thermal control is needed. This can be in the form of a thermo-electrically cooled enclosure. This will deal to a certain extent with the need to achieve analyzer wavelength repeatability. However, it does not address the issue of wavelength reproducibility between AOTF modnles, which impacts the transportability of calibrations and datasets between analyzers. 

Now we are going to give a physical insight into an origin of the mechanisms responsible for experimental results mentioned above. The physics of the temperature tuning of the VPC can be qualitatively understood in the framework of the model presented in the Section 12.1. The amplitude of the DFWM signal can be written as ... 

The fact that isomerization and relaxation processes are sensitive to the temperature of a specimen allows a combined optical-temperature control of azo-polymer third-order susceptibility. The temperature-tuned VPC is just one example of this. Combination of optical excitation and temperature variations may result in more effective governing linear and nonlinear optical properties of azo-dye polymer materials. 

Awangku Yusof, A. A. R., O Leary, S. V., and Mitchell, G. R. (1999). Temperature-tuned vector phase conjugation in azobenzene dye impregnated polymer films. Opt. Commun. 169, 333-340. 

Because diode lasers are compact and inexpensive, several units can be integrated and run simultaneously in a single spectrometer. Such parallel operation is necessary for simultaneous determinations of different species, because even if a single diode can be tuned to the analytical lines of various species, temperature tuning is too slow for many analytical applications. In addition, the duty cycle of a continuous-wave measurement is seriously reduced if several species must be measured sequentially with a single diode laser. 

Figure 10.4 High-resolution absorption spectrum of propane near 1.68 /xm measured by temperature-tuning a distributed feedback (DFB) diode laser Ptotai = 1 atm and T =...

S. V. Manorama, M. Nag, P. Basak, Low-temperature hydrothermal S3mthesis of phase-pure rutile titania nanocrystals Time temperature tuning of morphology and photocatalytic activity . Materials Research Bulletin, 42,1691-1704, (2007). 

Dzwolak W, Muraki T, Kato M, Taniguchi Y (2004) Chain-length dependence of alpha-heUx to beta-sheet transition in polylysine model of protein aggregation studied by temperature-tuned FTIR spectroscopy. Biopolymers 73 463-469... 

P. Walla, V. B. Arion, U. H. Brinker, Solvent- and temperature-tuned orientation of ferrocenyl azide inside jS-cyclodextrin, J. Org. Chem., 2006, 71, 3274-3277. 

Figure 6. Temperature tuning of Bragg diffraction from a 125-p,m-thick PCCA film of 99-nm polystyrene spheres embedded in a PNIPAM gel. The diffraction wavelength shift results from the temperature-induced volume change of the gel, which alters the lattice spacing. Spectra were recorded in a UV-visible-near IR spectrophotometer with the sample placed normal to the incident light beam (Adapted from ref 16).

Recent experiments, both in Houston and in Bonn, have shown, that temperature tuning of the diode laser can produce much better behaviour. Continuous scans of up to 5... 

The MBH adduct shown in Scheme 3.162, prepared from aromatic aldehydes and methyl acrylate, can directly undergo smooth dehydroxylation with concomitant olefin isomerization with low-valent titanium (LVT, prepared from TiCls-LAH-THF) reagent to afford the trisubstituted alkenes 364 with high ( )-selectivity. However, it is unsatisfactory in view of the low yield and the purity of products.More recently, Zhang et al. developed the samarium diiodide-promoted hydroxyl elimination of MBH adducts to form trisubstituted alkenes 364 with total ( )-stereoselectivity in good to excellent yields. This method also provided a new route to synthesizing a class of 1,5-hexadiene derivatives 365 by temperature tuning (Scheme 3.162). ... 

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