Programme

P.48 -- Poster, VCTP-47

Date: Thursday, 4 August 2022

Time: 08:30 - 10:00

Extracting asymmetricity of polar molecular from high order harmonic generation: effect of partial orientation

Kim-Ngan H. Nguyen (1), Ngoc-Loan Phan (2*), Cam-Tu Le (3), Van-Hoang Le (1)

(1) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam (2) Ho Chi Minh City University of Education, Ho Chi Minh City, Vietnam (3) Ton Duc Thang University, Ho Chi Minh City, Vietnam

Probing molecular asymmetricity is crucial to understanding the nature of polar molecules. Recently, we proposed a method to probe the intrinsic properties, particularly the intensities imbalance and the phase difference of adjacent attosecond bursts from experimental measurements of high-order harmonic generation (HHG) emitted from polar molecules interacting with an intense laser pulse [1]. This method's idea is based on retrieving these quantities directly from the time-frequency spectrogram constructed by the measured spectral intensity and phase of HHG. The advantage of this method compared with the one given in the previous study [2] is that our method requires measured data only and does not need pre-calculating quantities whose accuracy is strongly dependent on the level of theory. To probe the asymmetricity by HHG, the polar molecular sample must be aligned and oriented before interacting with a probe pulse. However, a perfect orientation and alignment are infeasible even with recent advanced techniques. This report presents an improvement of our method to incorporate the partial orientation of a molecular sample for retrieving the intensity imbalance and phase difference from its HHG. To develop this method, we analytically analyze the time-frequency of a single polar molecule and comparing with the one of a partially oriented sample constructed from HHG measurements. After acquiring the analytical formula, the inference of the intensity imbalance and phase difference of single polar molecular from experimental data of HHG emitted from a partially oriented sample is straightforward. Besides, the effect of the imperfect alignment on the method validation is also discussed. The results show that the improved method works reliably with general HHG experiments. [1] Kim-Ngan H. Nguyen, Ngoc-Loan Phan, Cam-Tu Le, Dinh-Duy Vu, Van-Hoang Le, 2022, in preparation. [2] E. Frumker, N. Kajumba, J. B. Bertrand, H. J. Wörner, C. T. Hebeisen, P. Hockett, M. Spanner, S. Patchkovskii, G. G. Paulus, D. M. Villeneuve, A. Naumov and P. B. Corkum, Phys. Rev. Lett., 2012, 109, 233904.

Presenter: Phan Ngoc-Loan