TAILIEUCHUNG - Sum frequency generation study of hydrated cellulose

Sum frequency generation (SFG) spectra of cotton cellulose fibers were successfully obtained with IR wavenumber from 2800 to 3400 cm-1 . The spectra showed the two peaks at 2840 cm-1 and 2941 cm-1 assigned to symmetric and asymmetric CH2 stretching modes, respectively. There was also a peak obtained at wavenumber 2959 cm-1 assigned to the overtone of H-O-C bending at Fermi resonance with 2941 cm-1 peak. | Sum frequency generation study of hydrated cellulose Nghiên cứu khoa học công nghệ SUM FREQUENCY GENERATION STUDY OF HYDRATED CELLULOSE Nguyen Duc Long1, Vuong Thi Quynh Huong1, Nguyen Van Kien2, Chu Văn Biên3, Nguyen The Binh1, Hoang Chi Hieu1* Abstract: Sum frequency generation (SFG) spectra of cotton cellulose fibers were successfully obtained with IR wavenumber from 2800 to 3400 cm-1. The spectra showed the two peaks at 2840 cm-1 and 2941 cm-1 assigned to symmetric and asymmetric CH2 stretching modes, respectively. There was also a peak obtained at wavenumber 2959 cm-1 assigned to the overtone of H-O-C bending at Fermi resonance with 2941 cm-1 peak. A spectral band of OH range appeared at 3322 cm-1. Hydration effects on cellulose were demonstrated on the SFG spectra of cellulose samples hydrated in different conditions. These results are the decrease in the peaks’ intensities and moreover the disappearance of two peaks. Explanation and discussion are shown in this paper. Keywords: Nonlinear optics, Sum frequency generation, SFG spectroscopy, Cellulose, Hydrated cellulose, Hydration, Hydrogen bonds. 1. INTRODUCTION Nonlinear optical spectroscopy has developed considerably in recent decades [1]. There have been a number of studies using Second Harmonic Generation (SHG) and Sum Frequency Generation (SFG) to probe surfaces and interfaces as nonlinear effects are forbidden in centrosymmetric environment [2][3]. On the other hand, SFG has high selectivity in molecular vibrational modes with orientation and sensitivity for chirality, thus it is a powerful tool to study biological molecules in the biomaterials [4][5][6]. Sum Frequency Generation is a second-order nonlinear optical response from a system where optical centrosymmetry is broken [7]. In SFG spectroscopy, the frequency of SFG signal is the sum of frequencies of two incoming beams, visible beam (VIS) and infrared beam (IR). The intensity is given by:

• Hoá học
• Sum frequency generation study of hydrated cellulose
• Sum frequency generation study
• Second harmonic generation
• Fermi resonance with 2941 cm 1 peak