Cristóbal Pérez | Searcharxiv

arXiv2025

Discovery of interstellar phenalene ($c$-C$_{13}$H$_{10}$): A new piece for the chemical puzzle of PAHs in space

We present the discovery of the unsubstituted polycyclic aromatic hydrocarbon (PAH) phenalene ($c$-C$_{13}$H$_{10}$) in TMC-1 as part of the QUIJOTE line survey. In spite of the low dipole moment of this three-ring PAH we have found a total of 267 rotational transitions with quantum numbers $J$ and $K_a$ up to 34 and 14, respectively, corresponding to 100 independent frequencies. The identification of this new PAH from our survey was based on the agreement between the rotational parameters derived from the analysis of the lines and those obtained by quantum chemical calculations. Subsequent chemical synthesis of this PAH and the investigation of its laboratory microwave spectrum unequivocally support our identification. The column density of phenalene in TMC-1 is (2.8$\pm$1.6)$\times$10$^{13}$ cm$^{-2}$.

astro-ph.GA↗

arXiv2021

State-specific Enrichment of Chiral Conformers with Microwave Spectroscopy

An interesting class of molecules is that in which the molecules do not possess a stereogenic center but can become chiral due to their spatial arrangement. These molecules can be seen as chiral conformers, whose two non-superimposable forms can interconvert from one another by rotations about single bonds. Here, we show that an initially racemic mixture of chiral conformers, such as a sample of cyclohexylmethanol, C$_{7}$H$_{14}$O (CHM), can be enantiomerically enriched by performing the enantio-selective process of coherent population transfer between rotational levels. By first performing a population transfer cycle, followed by a three-wave mixing experiment, we show that an enantiomeric excess in a rotational level of choice can be achieved. This represents the first experimental demonstration of such an effect in a chiral pair of conformers, and it showcases the broad applicability of three-wave mixing not only for analytical applications but also to a wide scope of experiments of fundamental interest.

physics.chem-ph↗