Mass‐Selected Circular Dichroism of Supersonic‐Beam‐Cooled [D4]‐(R)‐(+)‐3‐Methylcyclopentanone |
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Authors: | Jörn Lepelmeier Dr Katharina Titze Dr Aras Kartouzian Prof Ulrich Boesl Prof Ulrich Heiz |
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Institution: | Technische Universit?t München, Lehrstuhl für Physikalische Chemie, Garching, Germany |
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Abstract: | UV spectroscopy and electronic circular dichroism (ECD) experiments on supersonic‐beam‐cooled deuterated (R)‐(+)‐3‐methylcyclopentanone (D4]‐(R)‐(+)‐3‐MCP) have been performed by using a laser mass spectrometer. The spectral resolution not only allowed excitation and CD measurements for single vibronic transitions but also for the rotational P, Q, and R branches of these transitions. The investigated transition showed the largest anisotropy factor ever observed for chiral molecules in the gas phase, which, due to residual saturation of the excited transition, represents only a lower limit for the real anisotropy factor. Furthermore, one‐color (1+1+1) and two‐color (1+1′) resonance‐enhanced multiphoton ionization (REMPI) measurements were performed and the effusive‐beam (room temperature) and supersonic‐beam results for D4]‐(R)‐(+)‐3‐MCP were compared. These results allowed a differentiation between single‐step ECD (comparable to conventional ECD) and cumulative ECD (only possible in multiphoton excitation) under supersonic‐beam conditions. |
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Keywords: | circular dichroism mass spectrometry resonance-enhanced multiphoton ionization rotational spectroscopy supersonic beam cooling |
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