Empirical values of the ground state energies for methane transitions between 5500 and 6150 cm^−1

The strengths of more than 1600 lines of CH(4) have been measured in the spectral interval between 5500 and 6150 cm(-1) at room temperature and reduced temperatures. The variation of the measured strengths allows the energy of the lower state of the transition to be determined empirically using the temperature dependence of the methane partition function and the Boltzmann factor for the energy level populations. An error analysis, based on assumed errors in the strength and temperature measurements, is included. The average measured uncertainty in J is 0.2.