PRAMA Instruments Pvt. Ltd.
The deuterium lamp emits radiation extending from 112 nm to 900 nm,
although its continuous spectrum is only from 180 nm to 370 nm.
The spectrum intensity does not actually decrease from 250 nm to 200 nm .
The decrease in the plot is due to decreased efficiency at low wavelengths of the photo detector used to measure the lamp intensity.
The deuterium lamp's continuous spectrum is useful as both a reference in UV radiometric work and to generate a signal in various photometric devices.