I haven't been able to find the units of the reactive cross-section (σ* = Pσ) online but when I do a unit analysis from the equation:
$$ k = PσN_A √(\frac{8k_BT}{πμ}) e^{-E_a/RT}$$
then when plotting lnk against $1$/T the intercept is equal to:
$$intercept = lnPσN_A √(\frac{8k_BT}{πμ})$$
solving Pσ then gives that the units should be [m$^2$s$^{-1}$mol$^{-1}$]. However, the units of the collisional cross-section is [m$^2$] and the reactive cross-section is by definition the collisional cross-section times a steric factor P which is a constant, so how come the units change? Shouldn't the units for the reactive cross-section also be [m$^2$]?
