One Fairly Crude Method of Determining the Size of a Molecule

Multiple Choice

One fairly crude method of determining the size of a molecule is to treat the molecule as an infinite square well (a box) with an electron trapped inside, and to measure the wavelengths of emitted photons. If the photon emitted during the n = 2 to n = 1 transition has wavelength 1940 nm, what is the width of the molecule? (c = 3.00 × 10⁸ m/s, h = 6.626 × 10^-34J ∙ s, m_el = 9.11 × 10^-31 kg)

A) 1.33 nm
B) 1.12 nm
C) 1.21 nm
D) 1.45 nm