Submillimeter-Wave Spectroscopy of Phosphaalkynes: HCCCP, NCCP, HCP, and DCP

Area of Science:

• Physical Chemistry
• Spectroscopy
• Astrochemistry

Background:

• Unstable phosphorus-bearing molecules are crucial for understanding chemical processes in various environments.
• Investigating the rotational spectra of such molecules provides fundamental data on their structure and properties.

Purpose of the Study:

• To investigate the submillimeter-wave rotational spectra of HCCCP and NCCP.
• To determine molecular constants, including sextic centrifugal distortion constants, for these unstable molecules and their isotopomers.
• To analyze vibrational satellites for NCCP.

Main Methods:

• High-resolution submillimeter-wave spectroscopy using the Cologne Terahertz Spectrometer.
• In situ production of HCCCP and NCCP via pyrolysis reactions.
• Detection of isotopomers ((13)C and (15)N) and vibrational states (v(4)=1, v(5)=1 for NCCP).

Main Results:

• Measured rotational spectra for HCCP and NCCP in their ground vibrational states.
• Recorded vibrational satellites for NCCP in bending states v(4)=1 and v(5)=1.
• Detected ground state rotational spectra of (13)C and (15)N isotopomers of NCCP.
• Evaluated sextic centrifugal distortion constants for all investigated isotopomers and vibrational states.
• Observed transitions for HCP and DCP by-products.

Conclusions:

• The study provides precise spectroscopic data for HCCCP and NCCP, enhancing our understanding of small phosphorus-containing molecules.
• The determined molecular constants are valuable for theoretical calculations and astrophysical applications.
• The methodology allows for the characterization of other transient, reactive species.