Electron paramagnetic resonance (EPR) spectroscopy is the ideal method of choice when detecting and studying the wide variety of paramagnetic oxygen-centred radicals. For simple diatomic radicals, such as the superoxide (O₂⁻) or peroxy \( ({\text{ROO}}^{\bullet})\) species, the CW EPR profile (in particular the g-values) of these species can appear similar and indeed indistinguishable in some cases. Experiments using ¹⁷O-enriched oxygen, revealing a rich ¹⁷O hyperfine pattern, are therefore essential to distinguish between the two species. However, in many cases, particularly involving TiO₂ photocatalysis, the peroxy-type \( ({\text{ROO}}^{\bullet})\) radicals or other intermediate species such as the [O₂⁻…organic]-type adducts can be transient in nature and once again can produce similar g-values. In general terms, these reactive oxygen species (ROS) are formed and detected at low-temperature conditions. Hence, the application of EPR spectroscopy to studies of surface-stabilised oxygen-centred radicals must be performed under carefully selected conditions in order to confidently distinguish between the differing types of diatomic radicals, such as O₂⁻, \( {\text{ROO}}^{\bullet}\) or [O₂⁻…organic].

电子顺磁共振（EPR）光谱是检测和研究各种顺磁性氧中心自由基的理想选择方法。对于简单的双原子基团，如超氧化物（O ₂ ^- ）或过氧\（（{\文本{ROO}} ^ {\子弹}）\）物种，所述CW EPR轮廓（尤其是克的-值）这些在某些情况下，这些物种可能看起来相似，但实际上并没有区别。因此，使用富含¹⁷ O的氧气进行实验，揭示出富含¹⁷ O的超细图谱，对于区分这两种物质是必不可少的。但是，在许多情况下，尤其是涉及TiO ₂光催化的情况下，过氧型\（（{\ text {ROO}} ^ {\ bullet}）\）基团或其它中间物种，如〔O ₂ ^- ...有机]型加成物本质上可以是短暂的，并再次可以产生类似的克-值。一般而言，这些活性氧（ROS）是在低温条件下形成和检测的。因此，必须在精心选择的条件下将EPR光谱学应用于表面稳定的以氧为中心的自由基的研究，以便确信地区分不同类型的双原子自由基，例如O ₂ ^-，\（{\ text {ROO }} ^ {\ bullet} \）或[O ₂ ⁻ …organic]。