Vietnamese Scientists have taken dynamic photograph of N2 molecule

Posted at: MONday - 18/08/2014 15:14 - post name: Nguyễn Thị Thùy

Vietnamese Scientists have taken dynamic photograph of N2 molecule

Dr. Nguyen Ngoc Ty and Assoc. Professor – Dr .Le fromHo Chi Minh University of Education have succeeded in photographing the dynamic N2 molecular by tomography method using high-harmonic emission.

 Recently, the acquisition of information of molecular structure by sources of ultra short laser pulses has become one of the interesting research directions in the scientific community. When atoms or molecules interact with intense laser beams, one of the nonlinear optical effects is the emission occurs secondary waves (called high-harmonic generation, referred to as HHG). HHG generated by the combination ofprior ionized electron to the parent ion, so they brought information of molecular structure. In 2004, the image of outermost layer of electronic cloud (HOMO) of N2 molecules had been recreated from HHG data which generated by the interaction of molecules with infrared laser beam. The information of electronic cloud N2 was recorded in a femtosecond time scale, the time scalethat is happening molecular fluctuations should be viewed as dynamic information structure. The main success has attracted the interest of many research groups about the collection of information from the molecular structure of the HHG.

In this research, the authors re-create the image of HOMO and HOMO-1 of N2 molecules from HHG simulation. The purpose of this work is not only to verify the results of research but also provides to the reader a close relationship between image quality and renewable width of the flat region in the HHG spectrum, related closely to the wavelength of the laser beam.

By simulation, the authors test the results of the experimental dynamic photography of the outermost electron layer (HOMO) and the adjacent inner layer (HOMO-1) of N2 molecules from thehigh harmonic emission source due to interaction with intense laser beam ultrashort pulses. The simulation results match the experimental results. They also pointed out that to obtain HOMO images such as experimental results, the laser source needs wavelength to at least 1200 nm instead of 800 nm and with 2400 nm wavelength, the image would be perfect.

Translated by Nga Nguyen

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