本文利用Nd:YAG激光倍频光532 nm激光分成强度大致相等的两束激光作为泵浦光以2.73°交叉于碘分子样品室中，两束泵浦光发生干涉在碘分子中选择激发形成了空间正弦分布的激光态分子光栅和基态耗尽型光栅。另一束窄线宽染料激光作为探索光射入到激光感生光栅上，沿着布拉格衍射的方向接收信号光。利用泵浦共振为32-0R(55)，探索共振为13-0P(55)，R(55)和泵浦共振为32-0P(52)，探索共振为13-0P(52)，R(52)的碘分子双色激光感生光栅光谱谱线强度测定了127I的核自旋，测定值为5/2。

The two color laser induced grating spectroscopy (TC LIGS) technique is used for determination of the nuclear spin of 127I . The second harmonic output (532 nm) from a Nd:YAG laser is split into two pump beams with nearly equal intensity. These beams intersect at an angle of 2.73 degree and are directed into the I2 sample cell. The interference of these beams produces a sinusoidal distribution of a excited state laser induced population grating and a ground state laser induced depletion grating in the iodine molecules. A narrow bandwidth dye laser is used as probe beam and directed to the laser induced gratings. The spectroscopic signal is collected along the direction of Bragg diffeaction. The nuclear spin of 127I is determined by the pump resonance: 32-0 R(55), probe resonance: 13-0 P(55), R(55) and the pump resonance: 32-0 P(52), probe resonance: 13-0 P(52), R(52) TC-LIGs lines. The result is 5/2.