This page contains data files and models from "The evolution of the solar flux from 0.1 nm to 160 microns: quantitative estimates for planetary studies", Claire et al. 2012, published in the Astrophysical Journal.
IDL code can be dowloaded by clicking here. FORTRAN code is available upon request to the author. Please acknowledge the paper if you use the code and notify the author if you change the code substantially.
If you don't want to run the code yourself, here are relevant spectra for the top of the atmosphere flux at Earth at various times:
Spectra can be scaled to any solar system object by multiplying by (1/AU)2. Other ages? Run the code or contact Mark.
Note: These spectra are given in photochemical units and are the values directly on the grid points (i.e photons/cm^2/s/nm). The idl code will return this data in this format or, as an option, will bin the data to your favorite wavelength grid (as photons/cm^2/s or mW/m^2).