Hidden physics in molecular rovibrational spectrum

• An algebraic method for rotational energies (AMr) is proposed.
• The accurate rotational energies {ɛJ  } of 7Li27Li2 and NaF are obtained at first time.
• The accurate rovibrational interaction energies ευJint have been studied at first time.
• The error of the well known rigid rotor rotational energies has been studied.

An algebraic method for rotational energies (AMr) is proposed to unearth the rotational spectrum {ɛJ  } and the rovibrational interaction energies ευJint that are hidden in the rovibrational energies EυJ  . The applications to the excited electronic state a3Σu+ of 7Li27Li2 and the ground state X1Σ+ of NaF molecules show that: (1) the rotational energies ɛJ   of the lighter 7Li27Li2 molecule have better accuracies than the widely used rigid rotor rotational energies εJrr particularly for the lowest two rotational states, while the rigid rotor model produces satisfied rotational energies for the heavier NaF   molecule and (2) the attractive rovibrational interaction energies ευJint stabilize a molecular rovibrational system.

The figure shows the rovibrational interaction energies ευJint for the state a3∑u+ of 7Li27Li2 molecule, and indicates that the absolute values of rovibrational interactions are getting greater as either vibrational state υ or rotational state J   increases. The fact that all interaction energies ευJint are negative confirms that the rovibrational interaction energies are attractive, and that it is the rovibrational coupling makes the rovibrational energy EυJEυJ smaller than the sum Eυ+JEυ+J of its corresponding vibrational energy ευευ and the rotational energy εJεJ and makes the rovibrational system stableFigure optionsDownload as PowerPoint slide