Radiation of quanta

Number of molecules reacting Number of quanta of radiation absorbed ... 

Since RSA s for arbitrary wavelengths are not known, it is important to be able to design molecules which behave as a RSA at a desired wavelength. Briefly, the idea is to use a dimer molecule formed from monomers whose ground state absorption peaks near the wavelength of interest. If synthesis of the dimer with fixed orientation of the monomers at desired distances from one another is possible, and the dimer is sufficiently stable to withstand dissociation upon absorption of two quanta of radiation, and a number of other criteria are satisfied, the dimer may behave as a RSA at the desired wavelength. The dimer ground state absorption is to a state in which the excitation is spread over both monomeric units and the dimer excited state absorption commences from this state to the doubly excited electronic state in which both monomeric units are excited. 

There are two types of detectors quantum detectors, also known as photodetectors, and thermal detectors, which can be used in optical gas sensors (see Table 14.15). A quantum detector responds to individual photons, which are the quanta of radiation. A thermal detector responds to temperature changes caused by... 

As illustrated in Figure 10-1, the absorption of quanta of radiation by a molecule brings about transitions from its (normal) ground state to (a variety of) excited states. Spectroscopy is a procedure by which these absorptions can be mapped by instruments called spectrometers. 

No. of einsteins absorbed 1 Einstein = 1 mole of quanta of radiation... 

Nuclear magnetic resonance spectroscopy Interaction magnetic fields - nuclei Resonance of radiation quanta, h v Radiofrequency pulses Spectrum in time or frequency (FT) domain ... 

One quanta of high-frequency radiation — many quanta of low-frequency radiation... 

For the frequency which is effective in activating the molecules chemically N. hv ought to be equal to E, the energy of activation. (N is Avogadro s number.) From the heat of activation, therefore, we calculate the activating frequency by the relation v = EjNh. If the molecules really are activated by quanta of more or less monochromatic radiation the fact that the gas can absorb it should be manifested by the existence of an absorption band at this calculated frequency. 

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