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).

Methane’s 3ν1+ν3 vibrational overtone spectrum has been recorded at room temperature, 100 K, 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 Q(2) transitions. These results indicate the presence of several other bands whose intensities are derived through interactions with the 3ν1+ν3 vibrational overtone transition. Quantitative analysis of these interactions suggests a bright state origin of 11 277.0 cm−1.

Methane’s 3ν1+ν3 vibrational overtone transition centered at 8871 Å is studied with a molecular beam/Stark apparatus having 7.5 MHz Doppler limited resolution. First-order Stark splitting is observed for transitions between levels of E-type symmetry. From the measured splittings, we estimate the magnitude of the vibrationally induced dipole moment of the 3ν1+ν3 vibrational state.

Methane's 3nu1 + nu3 vibrational overtone transition centered at 8871 angstrom is studied with a molecular beam/Stark apparatus having 7.5 MHz Doppler limited resolution. First-order Stark splitting is observed for transitions between levels of E-type symmetry. From the measured splittings, we estimate the magnitude of the vibrationally induced dipole moment of the 3nu1 + nu3 vibrational state.

The vibrational overtone spectrum of propyne (CH3CCH) in the acetylenic CH Δv = 4 region was obtained by intracavity photoacoustic spectroscopy with a resolution limited by room-temperature Doppler broadening and pressure broadening. By comparison with a symmetric-top simulation, the observed spectrum was assigned as a rotationally resolved parallel band overlapped by a hot band.