This research focuses on the lifetime measurement of the high-lying 61 Σ g + excited state of sodium diatomic molecules with the presence of argon gas. Lifetime measurement is important since it provides accurate knowledge of the transition dipole moment which is a key parameter in determination of the probability of absorption and emission of light by a molecule. The excitation to the high-lying state was accomplished by two synchronized nano-second pulse dye lasers and decay fluorescence was studied using molecular spectroscopy technique. The detection was done by using combination of a spectrometer-PMT and a time-correlated photon-counting method. Lifetime measurements were done as a function of argon pressure and radiative lifetime was extracted. Spectroscopic technique has wide range of applications in physics, chemistry, biology, and astronomy. I will present the experimental technique and the lifetime measurement of the rovibrational level in the 61 Σ g + electronic state. This research is supported by the National Science Foundation (Award#1607601).

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Lifetimes of the first excited-state of sodium dimers are measured using time-resolved spectroscopy. Molecular fluorescence decay-time was recorded using time-correlated photon-counting technique and lifetime was extracted using a Stern-Volmer plot.