Determination of the rotational constant $A_0$ and the bending angle CNC for $CH_3NC$ and $CH_3^{15}NC$ molecules

Özet

The rotational constant $A_0$ for the ground state of $CH_3NC$ and $CH_3^{15}NC$ isotopomers is calculated using a technique which was used earlier for $CH_3CCH [9]$, $CH_3CN [10]$ and $SiH_3CCH [11]$. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the $\nu_8$ vibrational state, which is associated with the CNC bending vibration. These values of the moments of inertia are fitted with the values calculated from the rotational constant $B_V$ , found experimentally by measuring the rotational frequencies in the microwave and infrared regions. From the fitting, the rotational constant $A_0$, the bending angle $\angle$ CNC and the asymmetry parameter ${\cal K}$ are determined for $\nu_8$ = 1, 2 and 3 bending vibrational states. The effect of the isotopic substitution of $^{13}C$, $^{15}N$ and Deuterium on the angle a is studied, which is found to be negligible.