A satellite-borne imaging sensor uses a photodiode whose responsivity peaks at a wavelength of 590 nm, allowing it to detect emissions from sodium vapor in the upper atmosphere. Engineers plan to modify the photodiode’s semiconductor band-gap so that the peak responsivity shifts by 30 nm toward shorter wavelengths while keeping the spectral shape of the response curve otherwise unchanged.
(a) Calculate the new peak responsivity wavelength after the modification.
(b) Identify the perceived color corresponding to the new peak wavelength.
(c) Discuss qualitatively how the shift you calculated in part (a) will affect the sensor’s ability to detect natural sodium emissions at 589 nm. In your discussion, consider both the alignment (or misalignment) of peak responsivity with the emission line and the relative intensities detected before and after the modification.