Vibrational branching ratios and photoelectron angular distributions are reported for the 5sgr;minus;1photoionization channel of CO in the range 16 eVhngr;45 eV. Striking nonhyphen;Franckndash;Condon effects are observed in both the branching ratios and angular distributions as a result of various autoionizing states and a sgr; shape resonance that lie in this spectral range. The goal of the present measurement was to observe definitive evidence for the sgr; shape resonance via its nonhyphen;Franckndash;Condon effects on the vibrational ionization channels. Guided by recent calculations lsqb;Smith, Lynch, and McKoy, J. Chem. Phys.85, 6455 (1986)rsqb;, we examined the broad structure in the vibrational branching ratios and angular distributions in the range 25 eV hngr;40 eV. There, we found clear evidence for the sgr; shape resonance in the quantities bgr;(v+=0 and 1) and sgr;(v+=2)/sgr;(v+=0). Substantial differences between theory and experiment for the sgr;(v+=1)/sgr;(v+=0) branching ratio, however, serve to define the limitations of the current singlehyphen;channel picture for this process.
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