Question

A gas absorbs a photon of $355 nm$ and emits at two wavelengths. If one of the emissions is at $680 nm$, the other is at:

• A. $518 nm$
• B. $1035 nm$
• C. $325 nm$
• D. $743 nm$

Answer 1

Answer: (D)

$743 nm$

Answer 2

$\frac{1}{\lambda} = \frac{1}{\lambda_{1}} + \frac{1}{\lambda_{2}}$ $\frac{1}{355} = \frac{1}{680} + \frac{1}{\lambda_{2}}$ $\frac{1}{\lambda_{2}} = \frac{680 - 355}{355 \times 680}$ $\Rightarrow \lambda_{2} =743 nm$