Resonance Detection

The intensity of the energy emitted by the resonance detector is proportional to the intensity of the energy entering the detector from the optical path of the hollow cathode. The signal intensity from the hollow cathode is attenuated as it passes through the flame, as occurs with conventional atomic absorption instruments. The attenuated beam excites atoms in the atomic vapor of the resonance detector thus an emission signal is obtained which decreases as the concentration of the element aspirated into the flame increases. Calibration curves may be prepared in terms of absorbance units, as they are for conventional atomic absorption signals. 

FIGURE 10-31. Diagram of an atomic absorption spectrophotometer employing a resonance lamp as a monochromator. [From J. V. Sullivan and A. Walsh, The Application of Resonance Lamps as Monochromators in Atomic Absorption Spectroscopy, Spectrochim. Acta, 22, 1843 (1966). Used by permission of Pergamon Press.] 

The power supply to the hollow cathode source is modulated and an ac detection system is used. This arrangement prevents any radiation from the flame or resonance detector from producing an output signal. Random noise is less troublesome than in a conventional spectrophotometer. The resonance detector must, of course, produce a cloud of atomic vapor of the same element being aspirated into the flame. The hollow cathode source also must emit resonance lines of the same element. Analytical calibration curves closely parallel those obtained with conventional atomic absorption systems and sensitivities and detection limits are similar. 

---

J.J. Antel, Identification of Hydrogen in Materials by Resonance Detection of Neutrons , Watertown Ars, Mass TR 73-8 (1973)... 

Harbour, J.R. and Bolton, J.R. 1975. Superoxide formation in spinach chloroplasts electron spin resonance detection by spin trapping. Biochemical and Biophysical Research Communications 64 803-807. 

A. G. Marshall and C. L. Hendrickson. Fourier Transform Ion Cyclotron Resonance Detection Principles and Experimental Configurations. Int. J. Mass Spectrom., 215(2002) 59-75. 

Z. Li, H. Qiao, C. Lebherz, S. R. Choi, X. Zhou, G. Gao, H. F. Kung, D. J. Rader, J. M. Wilson, J. D. Glickson and R. Zhou, Creatine kinase, a magnetic resonance-detectable marker gene for quantification of liver-directed gene transfer. Hum. Gene Ther., 2005,16,1429-1438. 

Henry, Y., Ducrocq, C., Drapier, J. C., Servent, D., Pellat, C., and Guissani, A. (1991). Nitric oxide, a biological effector. Electron paramagnetic resonance detection of nitrosyl-iron-protein complexes in whole cells. Eur. Biophys. J. 20, 1-15. 

Reddy, D., Lancaster, J. R., Jr., and Comforth, D. P. (1983). Nitrite inhibition of Clostridium botulinum Electron spin resonance detection of iron-nitric oxide complexes. Science 221, 769-770. 

It is clear that the unmistakable resonance fingerprint provided by a narrow Lorentzian peak in the integral cross section (ICS) will be rare for reactive resonances in a collision experiment. However, a fully resolved scattering experiment provides a wealth of data concerning the reaction dynamics. We expect that the state-to-state differential cross sections (DCS) as functions of energy can be analyzed, using various methods, to reveal the presence of reactive resonances. In the following subsections, we discuss how various collision observables are influenced by existence of a complex intermediate. Many of the resonance detection schemes that have been proposed, such as the use of collision time delay, are purely theoretical in that the observations required are not currently feasible in the laboratory. Nevertheless, these ideas are also discussed since it is useful to have method available... 

Figure 7.8 Excitation (a) and detection (b) of the ion cyclotron motion within an FTMS mass analyzer cell. Reprinted from Marshall, A.G. and Flendrickson, C.L., Fourier transform ion cyclotron resonance detection principles and experimental configurations. International Journal of Mass Spectrometry, 215, 59-75. Copyright (2002), with permission from Elsevier.

Jaeger CD, Bard AJ (1979) Spin trapping and electron-spin resonance detection of radical intermediates in the photo-decomposition of water at TO2 particulate systems. J Phys Chem 83 3146-3152... 

Nearly all the efforts toward the application of double-resonance NQR to explosives detection have been driven by the problem of TNT detection [91,96,97], although reports on its application to RDX [98] and PETN [99] detection have appeared recently. Both of the double-resonance detection schemes described earlier have been applied to TNT detection, as it does not fit neatly into either category around the H frequency of 1 MHz, the proton and nitrogen T1 s are similar, with the proton T1 becoming much longer at higher frequencies there are multiple 14N NQRs the proton line width is greater than 10 000 Hz. 

D. B. Laubacher, Portable Nuclear Quadrupole Resonance Detection System for Detecting Presence of Explosives by Scanning Mail and Luggage, Uses High Temperature Superconductor Self Resonant Planar Transmit and Pick-Up Coil, US Patent Application No. US2004245988-A1 (2004). 

---