[Sadsura]

Hi i recently completed a lab experiment of decomposing the above product by dissolving in water and and a small amount 2M Sulphuric acid. it was then transferred into 2 test tubes.
the first tube was exposed to a 200W lamp for only 1 minute and the other for 10 minutes.afterwards few drops of K₃Fe(CN)₆ was added to each. results were
both clear light yellow solutions turned greenish blue for the first tube and the second was a more intense darkblue.

my question is, may i assume that the 200W lamp provided U.V radiation? the packets of energy (hv or h*frequency) was responsible for knocking out which electrons from which atom?

since Fe3+ decomposed to Fe2+, -electron is gained. i understand that 3 oxalate(bidentate) ions complexed with Fe 3+. did Fe3+  interact with packets of energy directly? or the bidentate ligands interacted with packets of light only instead or both Fe3+ and ligand?

may i humbly ask for an explanation of this photochemical decomposition. no need for maths but physics included in the answer is fine. from my perception,the complex formed forms a new energy variation whereby light absorbed breaks down smth in the complex. but its too general.