dark1 to dark6 were taken with the monochromator slits closed (10um), but the Xe arc lamp turned on and the output fibre connected.

These reveal the shape of the Xe arc lamp spectrum!

dark7 to dark11 were taken with the output fibre from the monochromator disconnected.

reference1 to reference8 were taken with the fibre connected, and slit width 100um

dark12 were taken after the references (to see whether exposing the spectrometer to bright light would affect subsequent readings)