The Lande \( g \)-factor is given by the formula:
\[
g = 1 + \frac{J(J+1) + S(S+1) - L(L+1)}{2J(J+1)}
\]
For \( ^2P_{3/2} \), we have \( S = \frac{1}{2}, L = 1, J = \frac{3}{2} \). Substituting these values:
\[
g = 1 + \frac{\frac{3}{2}(\frac{3}{2} +1) + \frac{1}{2}(\frac{1}{2} +1) - 1(1+1)}{2 \times \frac{3}{2} (\frac{3}{2} +1)}
\]
\[
= 1 + \frac{\frac{15}{4} + \frac{3}{4} -2}{\frac{15}{4}}
= 1 + \frac{16/4 - 8/4}{\frac{15}{4}}
= 1 + \frac{8}{15}
= \frac{3}{2}
\]