Oxygen isotope separation utilizing two-frequency infrared multiphoton dissociation of 2,3-dihydropyran

Oxygen isotope separation has been examined by utilizing the two-frequency infrared multiphoton dissociation (IRMPD) of 2,3-dihydropyran (DHP). The two-frequency IRMPD reduces the required laser fluences to those lower than the damage threshold of optical windows. For example, dissociation probability of DHP containing 18O (D(18O)) and enrichment factor (S) were obtained to be 1.6×10−3/pulse and 316, respectively, by the simultaneous irradiation with 1052.2 cm−1 photons at 0.45 J/cm2 and 1031.5 cm−1 photons at 1.06 J/cm2. These are comparable with D(18O)=2.2×10−3/pulse and S=391 obtained by the single-frequency irradiation of 1033.5 cm−1 photons at 2.2 J/cm2. Therefore, the production rate of an 18O enriched dissociation product has been increased to four times or more, compared with the single-frequency IRMPD, and this two-frequency method would promise a practical large scale separation.