Photoinduced reversible intramolecular hydrogen-atom migration between 9H-fluorene and 1H-fluorene isolated in an Ar matrix is found by FTIR spectroscopy with an aid of DFT calculation. The forward isomerization from 9H-fluorene to 1H-fluorene occurs upon UV irradiation (λ ≥ 295 nm), while the backward isomerization occurs upon λ ≥ 320 nm light irradiation. The less stable isomer, 1H-fluorene, is identified by comparison of the measured IR spectrum with the corresponding simulated spectral pattern obtained at the B3LYP/6-31++G(d,p) level. In addition, an IR spectrum of 9H-fluorene in the T₁ state is measured during UV irradiation (λ ≥ 275 nm).

借助DFT计算，通过FTIR光谱法发现在Ar基质中分离的9 H-芴与1 H-芴之间的光诱导可逆分子内氢原子迁移。从9正向异构化ħ芴至1本ħ发生芴在紫外线照射（λ ≥295纳米），而向后异构化时发生λ ≥320纳米的光照射。通过将测得的红外光谱与在B3LYP / 6-31 ++ G（d，p）水平获得的相应模拟光谱图进行比较，鉴定出不太稳定的异构体1 H-芴。另外，T _1中的9 H-芴的红外光谱状态下测量时紫外线照射（λ ≥275纳米）。