I am in the process of writing a C function for a Particle-In-Cell simulation framework. I am trying to implement a method for simulating photoelectrons. To do so, I need to be able to sample the solar spectrum in vacuum. In other words, if I have N photons, what is an accurate distribution of their frequencies?
Hello Tryam,
the solar spectrum in vacuum can be ideal approximated by a "black body" spectrum. The black body emission is described by the Planck distribution function. You need only the solar surface temperature (I believe nearly 5500 K). The Planck function you find in every textbook. Otherwise I can help.
With Regard
R. Mitdank
How accurately do you want your answer? As Rudiger states, just take the energy at some wavelength over a small finite bandwidth (if the bandwidth is zero you won't get a meaningful value) and get the number of photons in that band by dividing the energy at that wavelength (from the solar spectrum) by the energy of a single photon of the same wavelength.
If you want the intensity distribution of wavelength (reciprocal of frequency) for natural sunlight in vacuum, that is referred to as "air mass zero" and described by standardized values (ASTM and others). Tabulated values are published in several places. Try NREL's website at https://rredc.nrel.gov/solar//spectra/am0/
As Eric states, there are NREL publications which give energy density per unit wavelength. But you still have to convert this into photon count per unit wavelength as I described. But be careful about applying your results to ground level sensors. The air mass at ground level is usually called Air Mass 1.5 and deviates significantly from Air Mass Zero especially in the near IR.
- Badges
- Science topic