HIGH-RESOLUTION STUDY OF METHANES 3-NU(1)+NU(3) VIBRATIONAL OVERTONE BAND

Methane's 3v(1)+v(3) vibrational overtone spectrum has been recorded at room temperature, 100 KI and approximately 15 K using laser intracavity photoacoustic and molecular beam techniques. Although rotational congestion renders the room temperature spectrum undecipherable, the 100 K data suggest possible rovibrational assignments that are confirmed in the 15 K spectrum;by their individual temperature dependences. Molecular beam Stark spectroscopy is used to unambiguously identify the E symmetry components of the R(2), P(2), and e (2) transitions. These results indicate the presence of several other bands whose intensities are derived through interactions with the 3v(1)+v(3) vibrational overtone transition. Quantitative analysis of these interactions suggests a bright state origin of 11 277.0 cm(-1).