His work on the Morse/Long-range potential with his former student Nike Dattani of Oxford University was referred to as a "landmark in diatomic spectral analysis". In the landmark work, the C value for atomic lithium was determined to a higher-precision than any atom's previously measured  oscillator strength, by an order of magnitude.  This lithium oscillator strength is related to the radiative lifetime of atomic lithium and is used as a benchmark for atomic clocks and measurements of fundamental constants.