Tracking multiscale liquid crystal order with high harmonic spectroscopy
Abstract
Can high-harmonic generation track how microscopic intermolecular interactions give rise to macroscopic order? We address this question in the thermotropic liquid crystal 4-cyano-4'-n-pentylbiphenyl, a model system with a well-defined nematic-to-isotropic transition. Using a temperature-controlled flat jet, we show that polarization-resolved high-harmonic generation driven by mid-infrared strong-field pulses is highly sensitive to liquid-crystal order. In the nematic phase, the harmonic yield forms a four-lobed angular pattern with twofold rotational symmetry and is strongest when the driving-field polarization is perpendicular to the molecular director; this anisotropy vanishes in the isotropic liquid. A tight-binding model parameterized by first-principles calculations attributes this response to intermolecular orbital hybridization in short-range antiparallel molecular arrangements. Temperature-dependent measurements across multiple harmonic orders resolve the same first-order phase transition, with each harmonic order exhibiting a distinct optical sensitivity. A multiscale model combining the microscopic response, Landau-de Gennes orientational correlations and phase matching explains this behaviour through the interplay between orientational correlation lengths and harmonic coherence lengths. High-harmonic generation therefore links local electronic coupling to mesoscopic order and macroscopic propagation, providing an all-optical probe of multiscale organization in soft matter.
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BibTeX
@misc{murillosanchez2026tracking,
title = {{Tracking multiscale liquid crystal order with high harmonic spectroscopy}},
author = {Marta L. Murillo-Sánchez and Andrea Annunziata and Simon Vendelbo Bylling Jensen and Ángel Rubio and Caterina Vozzi and Thomas Pfeifer and Davide Faccialà and Nicolas Tancogne-Dejean and Laura Cattaneo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28128},
eprint = {2610.28128},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28128},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Tracking multiscale liquid crystal order with high harmonic spectroscopy
AU - Marta L. Murillo-Sánchez
AU - Andrea Annunziata
AU - Simon Vendelbo Bylling Jensen
AU - Ángel Rubio
AU - Caterina Vozzi
AU - Thomas Pfeifer
AU - Davide Faccialà
AU - Nicolas Tancogne-Dejean
AU - Laura Cattaneo
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28128
UR - https://arxiv.org/abs/2610.28128
AB - Can high-harmonic generation track how microscopic intermolecular interactions give rise to macroscopic order? We address this question in the thermotropic liquid crystal 4-cyano-4'-n-pentylbiphenyl, a model system with a well-defined nematic-to-isotropic transition. Using a temperature-controlled flat jet, we show that polarization-resolved high-harmonic generation driven by mid-infrared strong-field pulses is highly sensitive to liquid-crystal order. In the nematic phase, the harmonic yield forms a four-lobed angular pattern with twofold rotational symmetry and is strongest when the driving-field polarization is perpendicular to the molecular director; this anisotropy vanishes in the isotropic liquid. A tight-binding model parameterized by first-principles calculations attributes this response to intermolecular orbital hybridization in short-range antiparallel molecular arrangements. Temperature-dependent measurements across multiple harmonic orders resolve the same first-order phase transition, with each harmonic order exhibiting a distinct optical sensitivity. A multiscale model combining the microscopic response, Landau-de Gennes orientational correlations and phase matching explains this behaviour through the interplay between orientational correlation lengths and harmonic coherence lengths. High-harmonic generation therefore links local electronic coupling to mesoscopic order and macroscopic propagation, providing an all-optical probe of multiscale organization in soft matter.
ER -