Photon conversion factor

If an intensifier, such as the 85 mm presented here, is now replacing the screen, a relative gain of the order of x50 is obtained which results in a conversion factor of 1 to 7.5 (1 incident X photon --> 7.5 electrons). This conversion efficiency not only resolves the quantum sink problem but also increases the light level significantly to compensate for the low gamma fluxes obtained from radioactive sources. 

Putting in the values of h and c, we find the conversion factor from wavelength to photon energy is... 

Other units are more convenient when we are dealing with individual photon energies. It is common to use the electron volt (eV), equal to the kinetic energy imparted to an electron when it is accelerated in a potential of 1 V. The conversion factor between electron volts and joules is numerically equal to the charge on an electron ... 

Combining this with the above formulae gives the following conversion factor, when the photon energy is in electron volts, and wavelength in nanometres ... 

Table 1.1 Conversion factors between radiation frequency and wavenumber, photon energy, and the corresponding energy per moie...

This set of equations connects Planck s photon energy Ep with Einstein s mass/en-ergy equivalence, with Boltzmann s kinetic energy, with the kinetic energy of a particle and with the kinetic energy of an electron in an electric field of a voltage U of 1 V. The most important conversion factors used in photochemistry and photophysics are collected in Tab. 3-2. 

Cells were grown in 15 ml test tubes under a photon flux density of approximately 150/iE/mVs and were aerated (2wm) with ordinary air containing 20 ppm CO2. Linear growth rate was converted to CO2 fibcation rate (gC02/l/ y) mdtiplying the conversion factor (1.65). The conversion factor is calculated as follows 44(CO2)/12(carbon)X0.45(carbon content of cells). 

Combination of these conversion factors yields a composite factor of 50.35 for conversion of watts per cubic centimeter for the tungsten source to photons per square centimeter per second per wavenumber, with X stated in nanometers. 

Note that calculated energies are the first ionization energies per one atom because we used only one photon. To calculate the first ionization energies in eV as asked in the exercise, the above energies must be multiplied by the Avogadro s constant (to obtain the energies in J mof ) and then divided by the conversion factor 96485 J moT eV to obtain the values in eV ... 

DRS, the method of subtraction of the baseline requires special attention, especially because instructions in various commercial manuals might lead to erroneous results. The procedure adopted by the author involves (i) digital acquisition and storage of the reflectance spectrum of the white standard, Ro(v) over the range of wavenumbers v (cm1) of interest, where v = MX, X is the wavelength in cm and the conversion factor for the photon energy in... 

Conversion factor. A common conversion factor between exposure, absorbed dose, and dose equivalent is 1 R = 1 rad = 1 rem. This is an estimate that for radiation protection purposes is close enough (it actually over estimates the dose and therefore is a conservative estimate). The actual conversion is 1 R = 0.96 rem in tissue. Note that this method works only where the roentgen is defined - for photons of energy less that 3 MeV. When dealing with particulate radiation other methods must be used. 

As with charged particles, tables have been developed that provide a flux-to-dose-rate conversion factor as a function of photon energy (Table 16.3 and Fig. 16.1). Using the conversion factor C( ), Eqs. 16.12 and 16.13 take the... 

In this expression J is dimensionless, the half-life has units of seconds and the twentieth-power term in the numerator is a conversion factor with units of moles/photon. The integral overlap of the lamp emission and the chromophore electronic spectrum, EexZx, defines light absorption in photons mole-1 sec-1. EX is the average extinction coefficient for a given wavelength Interval with Zx equaling the lamp output over this same band. 

Photon flux-to-do.se conversions factors were calculated using the analytic expression provided in ANSI/ANS-6.1.1. The energy group structure, photon transport factors, and flux-to-dose conversions are listed in Table B-1. 

Table B-1. Photon transport factors and flux-to-dose conversion factors. 

Here, 0i is the angle of the incoming laser beam with respect to the surface normal. For a Nd YAG laser pulse (1064 nm) of duration t = 10 ps, intensity = 10 W/cm and area f = 1 mm (corresponding to a pulse energy of 100 pj), which irradiates a monolayer of molecules with a surface susceptibility of = 10 esu, one calculates from Eq. (6.14) about 10 photons per laser pulse. In the CGS system the susceptibility is defined via The conversion factor between the two systems... 

Use the energy per photon for yellow light found in part (a) as a conversion factor. 3.37 X 10 ) 1 photon SOLUTION ... 

Direct Photolysis. Direct photochemical reactions are due to absorption of electromagnetic energy by a pollutant. In this "primary" photochemical process, absorption of a photon promotes a molecule from its ground state to an electronically excited state. The excited molecule then either reacts to yield a photoproduct or decays (via fluorescence, phosphorescence, etc.) to its ground state. The efficiency of each of these energy conversion processes is called its "quantum yield" the law of conservation of energy requires that the primary quantum efficiencies sum to 1.0. Photochemical reactivity is thus composed of two factors the absorption spectrum, and the quantum efficiency for photochemical transformations. 

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