There could have been fluorescence that add intensity from other (usually smaller) wavelengths.

I presume "(usually longer lamdas)"

amd that would mean energy is lost by the absorption of part of the radiation

Smaller wavelength (Lamdas) has larger energy and higher frequency. These are adding energy to longer wavelengths. Sorry if my previous post was ambiguous.

@Hjalmar

Fluorescence occurs at a longer wavelength and therefore energy is lost when the original light is absorbed and light is then emitted