Knowledge Bank

The infrared spectrum of totally deuterated methane $CD4$ in the region from $930cm-1to1180cm-1$ has been recorded under high resolution $(0.003cm-1)$. i) The ground-state scalar rotational constants have been determined from the analysis of ground state combination differences: $Bo=2.632729(B)cm-1;Do=2.7635(45)10-5cm-1;Ho=0.869(90)10-9cm-1$. ii) The $\upsilon 2$ and $\upsilon 4$ bands have been reanalysed on the basis of a complete third-order hamiltonian. A set of only 16 new parameters is used to fit more than 1600 lines with a standard deviation of $0.004cm-1$. The most relevant upper state constants are: $ \begin{array}{ll} \upsilon_{2} = 1091.663 cm^{-1} & \upsilon_{4} = 997.876 cm^{-1}\ \Delta B_{2} = - 0.755 10^{-3} cm^{-1} & \Delta B_{4} = 0.122 10^{-3} cm^{-1}\ \zeta_{24} = 0.66322 & \zeta_{4} = 0.34020 \end{array}$ iii) 171 lines of the $\upsilon 4$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CD4$ have been assigned. Using the ground-state and $\upsilon 2$ constants of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CD4$, these lines are reproduced with a standard deviation of $0.0012cm-1$. The obtained constants are : $ \begin{array}{ll} \upsilon_{4}=989.251 cm^{-1} & \Delta B_{4} = 0.413 10^{-5} cm^{-1}\ \zeta_{4} = 0.3570 & \zeta_{24} = 0.6547 \end{array} $