4-氟間苯二酚及4-氯間苯二酚質量解析臨界游離光譜研究

Abstract

本論文應用質量解析臨界游離光譜術研究4-氟間苯二酚與4-氯間苯二酚的結構異構物陽離子振動。我們發現4-氟間苯二酚三個結構異構物，異構物A、B、C的第一電子激發態躍遷能分別測得為35121 ± 2 cm-1、35430 ± 2 cm-1、35412 ± 2 cm-1，它們的絕熱游離能分別為66964 ± 5 cm-1、67348 ± 5 cm-1、67269 ± 5 cm-1。而4-氯間苯二酚有兩個異構物A與B的第一電子激發態躍遷能，分別為34906 ± 2 cm-1與35148 ± 2 cm-1，其絕熱游離能為66792 ± 5 cm-1與67140 ± 5 cm-1。比較不同異構物的陽離子態光譜，我們發現結構異構物間電子躍遷能、游離能差異較大。分析光譜的譜峰我們得知這類陽離子的顯性振動以苯環部分的平面振動為主，不同異構物間相同的振動模式的頻率極為相近。Two-color resonant two-photon mass-analyzed threshold ionization (MATI) spectroscopy was applied to record the vibrationally resolved cation spectra of the selected conformational isomers of 4-fluororesorciol and 4-chlororesorcinol. Analysis of those MATI spectra gives the adiabatic ionization energies (IEs) of conformer A, B and C of 4-fluororesorcinol to be 66964, 67348 and 67269 cm-1, respectively, with an uncertainty of about 5 cm-1. 4-chlororesorcinol is found to have two conformers whose IEs are determined to be 66792 ± 5 and 67140 ± 5 cm-1. Analyzing obtained MATI spectra of these conformers we obtains the relative orientation of the hydroxyl group and find it has little effect on the in-plane ring vibration frequencies but has more obvious influences on electronic energy levels.