Inverse photon efficiency

CH radical and by the quantity of the (inverse) photon efficiency (D/XB ratio). This quantity describes the destruction events per emitted photon and is usually calculated with dissociation models. It will be convenient to quantify the formation of the C2Hy family in a similar manner. Section 4.5 discusses a correlation of the radiation of the carbon molecule (C2) with particle fluxes of C2Hy molecules. Results of measurements in a tokamak machine are presented as well as results from chemical erosion experiments in low pressure laboratory plasmas, which offer the opportunity to carry out systematic investigations at well defined parameters. 

Fig. 4.6. (Inverse) photon efficiency for the Fulcher radiation of hydrogen molecules as calculated by the present CR-model for FR. The curves represent lines of constant values for (Setf + DeS)/XBFui...

As described in Sect. 4.2.3 the (inverse) photon efficiency is the basis for the determination of particle fluxes from measured photon fluxes. For hydrocarbons, the destruction events are dissociation processes of the parent molecule. Following the discussion in the previous paragraphs two relations can be now defined (1) rcH4 = (-Deff/A B) 4 x and (2) Tc2hh = ( Deff/Xx r. These correlations offer a method to quantify the methane flux as well as the flux of the higher hydrocarbons which are re-... 

Recently, Zewail and co-workers have combined the approaches of photodetachment and ultrafast spectroscopy to investigate the reaction dynamics of planar COT.iii They used a femtosecond photon pulse to carry out ionization of the COT ring-inversion transition state, generated by photodetachment as shown in Figure 5.4. From the photoionization efficiency, they were able to investigate the time-resolved dynamics of the transition state reaction, and observe the ring-inversion reaction of the planar COT to the tub-like D2d geometry on the femtosecond time scale. Thus, with the advent of new mass spectrometric techniques, it is now possible to examine detailed reaction dynamics in addition to traditional state properties." ... 

A common cause of inaccuracy in SPC-based time domain detection is pulse-pileup, that is, the arrival of photons during the dead-time of the detection system. Because the higher probability of emission (and detection) in the earlier part of the decay, pulse-pileup is more probable in this part of the decay. Consequently, the decay will be distorted and the lifetime will be biased towards higher values. Moreover, pulse-pileup will also result in a reduction of the detection efficiency (see Fig. 3.7 and Eq. (3.4)). Therefore, care should be taken to avoid excitation rates too close to the efficacy count rate (i.e., the inverse of the dead-time) in order to minimize these effects. 

As a hrst experiment, we wanted to return to the fundamental premise of TPM, which states that the efficiency of the two-photon excitation should be inversely proportional to the pulse duration. For TL pulses it is equivalent to having two-photon excitation efficiency proportional to the spectral bandwidth of the laser pulses. 

Two-photon fluorescent (TPF) detection, which was initiated by a non-linear optical absorption process, has been performed on a quartz chip. Since the fluorescent efficiency in TPF is inversely proportional to the excitation beam area, the path length dependence problem in fluorescence is significantly reduced. This method is used for analysis of P-naphthylamine (excitation at 580 nm), which is the enzymatic product of leucine aminopeptidase (LAP) acting on the fluorogenic substrate leucine P-naphthylamide [675],... 

Since the depletion depth is inversely proportional to net electrical impurity concentration, and since counting efficiency is also dependent on the purity of the material, large volumes of very pure material are needed to ensure high counting efficiency for high energy photons. 

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