Question

Why is spectrofluorometry potentially more sensitive than spectrophotometry?

Short answer

The intensity of the light transmitted by the spectrophotometer is measured relative to the intensity of the light transmitted by the blank, but the intensity of the light transmitted by spectrofluorometry is measured absolute, making it more sensitive.

Step-by-step solution

Step 1. Given information

They are comparing two different phenomenons on the basis of sensitivity.

Step 2. Reason why spectrofluorometry potentially more sensitive than spectrophotometry 

Fluorescence spectroscopy has a $1$to $3$order of magnitude better sensitivity than spectrophotometry (absorption spectroscopy). Single molecules can also be identified using fluorescence spectroscopy under controlled circumstances for a given species. In fluorescence approaches, the linear concentration range is substantially greater than in spectrophotometry. Spectrophotometry can only be used in the UV-visible range, but spectrofluorometry can alter filter selection and wavelength range.

The intensity of the light transmitted by the spectrophotometer is measured relative to the intensity of the light transmitted by the blank, but the intensity of the light transmitted by spectrofluorometry is measured absolute, making it more sensitive.