Optically detected magnetic resonance sensitivity

A number of other laser spectroscopic techniques are of interest but space does not permit their discussion. A few specialized methods of detecting laser absorption worthy of mention include multiphoton ionization/mass spectrometry (28), which is extremely sensitive as well as mass selective for gas-phase systems optically detected magnetic resonance (29) laser intracavity absorption, which can be extremely sensitive and is applicable to gases or solutions (30) thermal blooming, which is also applicable to very weak absorbances in gases or liquids (31) and... 

PLE) spectra. Optically detected magnetic resonance (ODMR), a variant of the PL technique, is also a very effective method, especially in identifying the nature of the defects involved. A typical PL apparatus is shown in Figure 3.1 and is composed of a light source for excitation (typically a He-Cd laser for ZnO), a sample holder, a dispersive element (grating monochromator), and an optical detector sensitive to the dispersed light. 

Electrically-detected magnetic resonance has been used with Si P to sensitively probe nuclear spins with pulsed ENDOR at high and low magnetic fields/ High magnetic fields have been used to polarize Si P electron spins and this has been transferred to nuclear spins with optical excitation and entirely electrically/ As shown in Fig. 1, EDMR has been used to show that strain is useful for tuning Si P resonance frequencies. ... 

Slow-passage ODMR signals frequently are observed by the continuous wave method in which the optical effect is monitored using broadband detection. On the other hand, if the triplet state decay constants are sufficiently large, the microwave power may be amplitude modulated at an audio frequency which results in modulated phosphorescence when the microwave frequency is at resonance. The phosphorescence is then monitored with narrow-band phase-sensitive detection, for a great improvement in the signal/noise ratio. The latter detection method is frequently used to produce a magnetic resonance-induced phosphorescence spectrum by a technique referred to as phosphorescence-microwave double resonance (PMDR). The microwave frequency is fixed at resonance,... 

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