Project Title: From Stereodynamic Imaging, Roaming Signature, Halogen Elimination to Lipid Dynamics at a Single-Molecule Leve（1/3）

Funding Organization:

Project Number: 108-2113-M-002-008-

Start & Expected Completion date: 2019/08/01 - 2020/07/31

Keyword：Orientation; Photodissociation; Roaming mechanism

Abstract：

In this three-year proposal, we plan to conduct four projects:

1. Stereodynamic imaging of photofragments from oriented chiral molecules,

2. Roaming signature in photodissociation of carbonyl compounds in conjunction with hexapole state selector,

3. Hetero-halogen elimination and halogen-channel competition by cavity ring-down absorption spectroscopy, and

4. Liposome dynamics probed by single-molecule fluorescence correlation spectroscopy: dependence of vesicle size and structure phase.

In the first subject, we will focus on differentiation of 2-bromobutane enantiomers in S- and R-form. A sliced ion imaging will be applied for photofragment detection, while the individual enantiomer is oriented with hexapole state selector coupled with DC field. A single or dual lasers experiment will be carried out for photodissociation of enantiomer,followed by (2+1) REMPI acquisition of either Br or Br*. Then, the ion images will be analyzed to obtain recoil frame angles and the subsequent photofragment angular distribution for chirality recognition.

In the second subject, we plan to apply a photolysis-probe technique to CH3CHO molecules which will be oriented with hexapole state selector. Following photolysis at 248 nm, the CO fragment will be probed with (2+1) REMPI scheme at ~230 nm. The J-dependence of translational energy distribution will be analyzed in comparison with the results but without molecular orientation. Meanwhile, in collaboration with Bowman and Han, the QCT calculations on a full dimensional PES will be performed according to the experimental conditions.

In the third project, we will carry out photodissociation of CHBr2I at 248 nm followed by spectral acquisition of Br2 and BrI fragments using CRDS. First of all, we will collaborate with Prof. Liang group to synthesize the compound which will be separated and purified to remove side-products to the minimum extent. Then, we will analyze the rovibrational spectra of these two fragments and evaluate the branching ratio of each fragment. From the theoretical point of view, we will estimate the branching ratio of these two fragments for comparison with the experimental value and then elucidate the results.

In the fourth project, we will synthesize two types of SUVs, DPPC and DOPC, with various vesicle sizes from 10 to 100 nm with involvement of silica bead. We will look into influence of vesicle size on the diffusion properties of the SUVs and the DiD triplet state lifetime. Following the similar experiments, the lipid dynamics of DPPC and DOPC with different phase will be studied. A similar plot of diffusion rate versus triplet lifetime will be analyzed and compared between different lipid composition to find out phase influence on the photodynamic and diffusion properties of DiD in SUVs.

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Photolysis Dynamics Laser Chemistry Lab

雷射反應動力學實驗室

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