Using the relation E = hν, which implies ν = E/h, and the given values E = 1.326 eV = 1.326 × 1.6 × 10⁻¹⁹ J and h = 6.63 × 10⁻³⁴ J·s, we calculate ν as follows: \[ u = \frac{1.326 \times 1.6 \times 10^{-19}}{6.63 \times 10^{-34}} \approx 3.20 \times 10^{14}\,\text{Hz} \]