# SURFACE ELECTRON EJECTION BY LASER-EXCITED METASTABLE SPECTROSCOPY OF $C_{2}H_{2}$

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 Title: SURFACE ELECTRON EJECTION BY LASER-EXCITED METASTABLE SPECTROSCOPY OF $C_{2}H_{2}$ Creators: Altunata, Selen; Cunningham, Kevin L.; Drucker, Stephen; Morgan, Christopher G.; Field, R. W. Issue Date: 1998 Publisher: Ohio State University Abstract: The triplet states of $C_{2}H_{2}$ reported in J. Chem. Phys. 107, 49 (1997) have been recorded at higher resolution, providing new insight into intersystem crossing in $C_{2}H_{2}$. LIF is combined with Surface Electron Ejection by Laser-Excited Metastables (SEELEM or LEM for short) to provide complementary information about the these states. In SEELEM spectroscopy, a metastable molecule in a molecular beam is detected by the observation of an electron ejected as the excited molecule impacts a metal surface. For an electron to be ejected, the excited state must have a lifetime on the order of the flight time $(\sim 100 \mu s)$ and must have an electronic energy that exceeds the work function of the surface. LIF detects states with short lifetimes due to large amounts of singlet character. SEELEM detects states with long lifetimes due to large amounts of triplet character. Further, SEELEM only detects the portion of the triplet character from triplet basis states with more excitation energy than the work function of the metal. The simultaneously recorded spectra are used to determine the electronic character of eigenstates. Description: Author Institution: Department of Chemistry, Massachusetts Institute of Technology URI: http://hdl.handle.net/1811/19079 Other Identifiers: 1998-TG-12