Tuneability

In the analysis of vibration data there is often the need to transform the data from the time domain to the frequency domain or, in other words, to obtain a spectrum analysis of the vibration. The original and inexpensive system to obtain this analysis is the tuneable swept-filter analyzer. Because of inherent limitations of this system, this process, despite the use of automated sweep, is time-consuming when analyzing low frequencies. When the spectra data needs to be digitized for computer inputing, there are further limitations in capability of tuneable filter-analysis systems. 

Blomberg, M., A. Torkkeli, A. Lehto, C. Helenelund, M. Viitasalo. Electrically Tuneable Micromachined Fabry-Perot Interferometer in Gas Analysis. Phystca Scripta T69 (1997), pp. 119-121. 

Concurrent with these investigations, polyphosphazene matrices, functionalized with aminoacid esters or with imidazole groups, became of importance because of their tissue engineering aspects in bone regeneration [655,656,679], treatment of periodontal diseases [657], and nerve reconstruction problems [680-682] in which the remarkable bio compatibility of POP matrices was coupled with their tuneable bio degradability. 

Walter, M. and Hakkinen, H. (2006) A hollow tetrahedral cage of hexadecagold dianion provides a robust backbone for a tuneable sub-nanometer oxidation and reduction agent via endohedral doping. Physical Chemistry Chemical Physics, 8, 5407-5411. 

Remarkably the position of the final plasmon peak of the alloy particles is dependent on the molar ratio of gold to silver nanoparticles. When the ratio is shifted favoring either metal, an alloy of any desired composition can be formed. This alloying phenomenon indicates that it is possible for true tuneability of the properties of a set of nanoparticles. 

High solvating power, tuneable via mechanical compression... 

Extraction selectivity (tuneable solvent strength p, T, modifier)... 

This chapter deals mainly with (multi)hyphenated techniques comprising wet sample preparation steps (e.g. SFE, SPE) and/or separation techniques (GC, SFC, HPLC, SEC, TLC, CE). Other hyphenated techniques involve thermal-spectroscopic and gas or heat extraction methods (TG, TD, HS, Py, LD, etc.). Also, spectroscopic couplings (e.g. LIBS-LIF) are of interest. Hyphenation of UV spectroscopy and mass spectrometry forms the family of laser mass-spectrometric (LAMS) methods, such as REMPI-ToFMS and MALDI-ToFMS. In REMPI-ToFMS the connecting element between UV spectroscopy and mass spectrometry is laser-induced REMPI ionisation. An intermediate state of the molecule of interest is selectively excited by absorption of a laser photon (the wavelength of a tuneable laser is set in resonance with the transition). The excited molecules are subsequently ionised by absorption of an additional laser photon. Therefore the ionisation selectivity is introduced by the resonance absorption of the first photon, i.e. by UV spectroscopy. However, conventional UV spectra of polyatomic molecules exhibit relatively broad and continuous spectral features, allowing only a medium selectivity. Supersonic jet cooling of the sample molecules (to 5-50 K) reduces the line width of their... 

Hyperthermal surface ionisation (HSI) is an ultrasensitive tuneable selective ion source [222,223] which is based on the very effective ionisation of various hyperthermal molecules upon their scattering from a surface with a high work function, such as rhenium oxide. Molecule-surface electron transfer constitutes the major and most important HSI mechanism for GC-MS. 

Detection limits in the lOOfg range can be obtained with a tuneable UV laser working at a wavelength of maximum absorption for the compounds of interest. Continuous supersonic beams require high gas loads and combination with a pulsed ionisation technique (e.g. REMPI) is unfavourable in terms of sensitivity. Pulsed valves are a better approach for a GC-UV-MS interface [1021]. 

A XAS experiment involves the irradiation of a sample with a tuneable source of monochromatic X-rays, usually from a synchrotron facility (high brilliance). Third-generation synchrotrons have sufficient intensity to observe XAFS spectra up to 100 keV. Nevertheless, laboratory-scale XAFS spectroscopy is of importance, despite the vast availability of synchrotron beam time [305]. 

Accelerator mass spectrometry Acousto-optical tuneable filter Acousto-optical tuneable spectrometer/scanning Atom probe... 

The analysis of carotenoid identity, conformation, and binding in vivo should allow further progress to be made in understanding of the functions of these pigments in the photosynthetic machinery. One of the obvious steps toward improvement could be the use of continuously tuneable laser systems in order to obtain more detailed resonance Raman excitation profiles (Sashima et al 2000). This technique will be suitable for the investigation of in vivo systems with more complex carotenoid composition. In addition, this method may be applied for the determination of the energy of forbidden Sj or 2 Ag transition. This is an important parameter, since it allows an assessment of the energy transfer relationship between the carotenoids and chlorophylls within the antenna complex. 

Vogt, C., Toprak, M.S., Muhammed, M., Laurent, S., Bridot, J.L. and Muller, R.N. (2010) High quality and tuneable silica shell-magnetic core nanopartides. Journal of Nanoparticle Research, 12 (4), 1137-1147. 

Thus, the region 2100-1830 cm 1 can be covered. This allows us to monitor CO(v,J) by resonance absorption and various M(CO)n [n = 3-6] as a result of near coincidences between the CO laser lines and the carbonyl stretching vibrations of these species. The temporal response of the detection system is ca. 100 ns and is limited by the risetime of the InSb detector. Detection limits are approximately 10 5 torr for CO and M(CO)n. The principal limitation of our instrumentation is associated with the use of a molecular, gas discharge laser as an infrared source. The CO laser is line tuneable laser lines have widths of ca. lO cm 1 and are spaced 3-4 cm 1 apart. Thus, spectra can only be recorded point-by-point, with an effective resolution of ca. 4 cm 1. As a result, band maxima (e.g. in the carbonyl stretching... 

The tuneable nature of the evanescent field penetration depth is critical to the effective operation of this sensor as it facilitates surface-specific excitation of fluorescence. This means that only those fluorophores attached to the surface via the antibody-antigen-labelled antibody recognition event... 

While planar optical sensors exist in various forms, the focus of this chapter has been on planar waveguide-based platforms that employ evanescent wave effects as the basis for sensing. The advantages of evanescent wave interrogation of thin film optical sensors have been discussed for both optical absorption and fluorescence-based sensors. These include the ability to increase device sensitivity without adversely affecting response time in the case of absorption-based platforms and the surface-specific excitation of fluorescence for optical biosensors, the latter being made possible by the tuneable nature of the evanescent field penetration depth. 

Figure 8.3 Structural formula of the phthalocyanine macrocycle and its chemically tuneable positions.

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