Spectroscopy cavity ring-down

If radiation of a particular wavelength I, or wavenumber v, of intensity /q enters a cell of length I, containing an absorbing sample, and emerges from the cell with reduced intensity /, the absorbance A is given by  

Using napierian logarithms (loge = In), Equation (9.27) can be rewritten  

In the this form the Beer-Lambert law shows that the intensity of radiation transmitted by an absorbing sample declines exponentially as the length over which the absorption takes place increases. If the radiation, travelling with the speed of light c, takes time tg to traverse the absorbing path f Equation (9.29) becomes  

The fact that the transmitted intensity decreases exponentially with time forms the basis of cavity ring-down spectroscopy (CRDS). 

The pulses of radiation are said to ring backwards and forwards between the mirrors and the time for the signal to decrease to 1/e of its original value is called the ring-down time of the cavity hence the name cavity ring-down spectroscopy. 

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Zalicki P and Zare R N 1995 Cavity ring-down spectroscopy for quantitative absorption-measurements J. Chem. 

Lehmann K K and Romanini D 1996 The superposition principle and cavity ring-down spectroscopy J. Chem. Phys. 105 10,263-77... 

New to the fourth edition are the topics of laser detection and ranging (LIDAR), cavity ring-down spectroscopy, femtosecond lasers and femtosecond spectroscopy, and the use of laser-induced fluorescence excitation for stmctural investigations of much larger molecules than had been possible previously. This latter technique takes advantage of two experimental quantum leaps the development of very high resolution lasers in the visible and ultraviolet regions and of the supersonic molecular beam. 

Schoemaecker Moreau, C. et al.. Two-color laser-induced incandescence and cavity ring-down spectroscopy for sensitive and quantitative imaging of soot and PAHs in flames, Appl. Phys. B, 78,485,2004. 

Schocker, A., Kohse-Hoinghaus, K., and Brockhinke, A., Quantitative determination of combustion intermediates with cavity ring-down spectroscopy Systematic study in propene flames near the soot-formation limit, Appl. Opt., 44, 6660,2005. 

Materials CRDS cavity ring down spectroscopy... 

Pipino, A. C. R., J. W. Hudgens, and R. E. Huie, Evanescent Wave Cavity Ring-Down Spectroscopy for Probing Surface Processes, Chem.. Phys. Lett, 280, 104-112(1997). 

CAVITY RING-DOWN SPECTROSCOPY DO YOU HAVE AN ULCER ... 

M. W. Todd, J. Glasser, A. A. Kachanov, B. A. Paldus, T. G. Spence, and R. N. Zare, "Stable Isotope Ratios Using Cavity Ring-Down Spectroscopy Determination of, C/I2C for Carbon Dioxide In Human Breath,"... 

New boxed applications include an arsenic biosensor (Chapter 0). microcantilevers to measure attograms of mass (Chapter 2), molecular wire (Chapter 14), a fluorescence resonance energy transfer biosensor (Chapter 19), cavity ring-down spectroscopy for ulcer diagnosis (Chapter 20), and environmental mercury analysis by atomic fluorescence (Chapter 21). 

Pipino, A.C.R., Hudgens, J.W. and Huie, R.E. Evanescent wave cavity ring-down spectroscopy for probing surface processes, Chem. Phys. Lett., 280, 104 (1997). 

Q The use of cavity ring-down spectroscopy has especially intrigued you. Can you describe this technique ... 

Fig. 1.47. Absorption spectrum of gold atoms deposited on an amorphous silica surface investigated by cavity ring-down spectroscopy...

Cavity Ring-Down Spectroscopy was introduced in 1988 by O Keefe and Deacon as a spectroscopic method for absorption measurements (O Keefe and Deacon, 1988). It is a versatile high sensitivity absorption technique. One of the most essential advantages of CRDS in contrast to usual absorption methods is that the CRDS signal is not affected by intensity fluctuations of the laser since only the decay time of the signal, which does not depend on the laser intensity, is detected. 

Berden Q., R. Peelers and G. Meijer Cavity ring-down spectroscopy Experimental schemes and applications, Int. Rev. in Phys. Chem. 19 (2000) 565-607. 

Romanini D., A. A. Kachanov, N. Sadeghi and F. Stoeckel CW cavity ring down spectroscopy, Chem. Phys. Lett. 264 (1997a) 316-322. 

SiH2 is a highly reactive species which may undergo fast insertion reactions into o bonds and addition reactions to n bonds. The available work on the elementary reactions of SiH2 up to 1994 has been reviewed in detail by Jasinski et al. Because of its intense and well-resolved Bi <— Ai electronic absorption in the visible spectrum,SiH2 is easily detected with high sensitivity by laser-induced fluorescence, laser resonance absorption flash kinetic spectroscopy, or cavity ring-down spectroscopy. These techniques... 

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