Cavity ring down

O Keefe A and Deacon DAG 1988 Cavity ring-down optical spectrometer for absorption-measurements using pulsed laser sources Rev. Sol. Instrum. 59 2544-51... 

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... 

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

Figure 9.36 Schematic diagram showing how a cavity ring-down absorption spectrum is obtained...

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. 

Figure 9.37 Cavity ring-down absorption spectrum of O2, showing part of the 1-0 band of the system. (Reproduced, with permission, from O Keefe, A. and Deacon, D. A. G., Rev. Sci. Instrumen., 59, 2544, 1988)...

Figure 9.39 Cavity ring-down absorption spectrum showing (below) the 0-0 band of the A n /2-...

Figure 9.40 Cavity ring-down absorption spectrum of HCN showing the overtone/combination band. (Reproduced, with permission, from Romanini, D. and Lehmann, K. K., J. Chem. Phys., 99, 6H1, 1993)...

In a cavity ring-down absorption experiment the length of the cavity is 1.24 m. What is the time interval between the detected signals ... 

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. 

For an RF electric field sensor, bandwidth (speed) is another important requirement. The speed of a resonator is determined by the cavity ring down time r = QX/c. As in any devices using resonating structures, a trade off between sensitivity (which increases with Q) and speed (which decreases when Q increases) has to be made. At the wavelength of 1.55 pm, Q factors of 104 and 106 translates to a sensor bandwidths of 20 GHz and 200 MHz, respectively. 

Materials CRDS cavity ring down spectroscopy... 

FIGURE 5.9 Schematic diagram of a cavity ring down apparatus (adapted from Paul and Saykally, 1997). 

Thus measurement of the cavity ring down times in the presence and absence of the absorbing gas allows the absorption of the gas to be obtained, and from A = (1 - e aNL) aNL, the concentration of the gas determined. These concentrations as a function of time therefore allow the reaction kinetics of the absorbing species to be determined. 

Atkinson, D. B and J. W. Hudgens, Chemical Kinetic Studies Using Ultraviolet Cavity Ring-Down Spectroscopic Detection Self-Reaction of Ethyl and Ethylperoxy Radicals and the Reaction 02 + C2H5 - C2H502, J. Phys. Chem. A, 101, 3901-3909 (1997). 

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). 

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