[[alternative]]Electron Paramagnetic Resonance Studies of Some Paramagnetic

[[abstract]]NH3+ 和 SeO43-, SeO4-, SeO3-, SeO2- 等這些自由基以往都是用游離輻 射照射晶體產生的，含銨化合物晶體經紫外光照射也會產生這些自由基。 其中 NH3+ 自由基是晶體中 NH4+ 離子經紫外光照射後解離而產生的； SeO43-、SeO3-、 SeO2- 等自由基則是由晶體中 NH4+ 離子與 SeO42- 離 子經紫外光照射後發生氧化還原反應所產生的。 MASD:CrO42- 晶體與含 CH3NH3+ 離子的 K-alum:CrO42- 晶體經紫外光照射後，晶體中的 CrO42- 離子會發生還原反應產生 CrO43- 離子，反應中所需的電子是由 CH3NH3+ 離子經紫外光照射後解離出來的光電子。 所以利用紫外光照射 晶體也是一種可以使 CrO42- 離子還原成 CrO43- 離子的方法。 KDP 和 ADP 晶體在室溫下經γ射線照射後， 會出現由磷酸根離子所產生的自由 基。晶體中的 CrO42- 雜質可以有效地穩定這些經輻射破壞產生的自由基 。BDP 晶體在室溫下經γ射線照射後也會產生類似的自由基。實驗結果顯 示，磷酸鹽晶體經輻射破壞所產生的是 [PO5]2- 或 [O3POO]2- 自由基。 甲基銨鋁明礬 (MASD) 晶體一般是屬於β型結構。由實驗發現，在晶體的 生長溶液中摻入 ClO4- 雜質，可以培養出α型結構的晶體。 此化合物之 同分異構物可以利用 X 射線粉末繞射分析以及摻入晶體中之 Cr3+ 離子 的 EPR 譜線加以區分。 在α型和β型結構的晶體中， Cr3+ 離子的 EPR 譜線都有線寬變化異常的現象，但其成因則有所不同。 Oxyradicals of Selenium and NH3+ radical are conventionally produced via γ - or X-irradiation. These radicals can be produced by UV-irradiation in some ammonium compounds. The NH3+ radical is produced by the UV photo- dissociation of the NH4+ ion in solids. The oxyradicals of selenium can be regarded as the product of the UV photo-redox reaction between the NH4+ ion and SeO42- ion. CrO43- ion can be produced by UV irradiation in single crystals of chromate- doped MASD and in K-alum lightly codoped with the CH3NH3+ ion. The photoreduction is a simple reduction of the type CrO42- + e- → CrO43-, where the odd electron is a photoelectron liberated by the CH3NH3+ ion. The CrO42- impurity has been found to be very effective in stabilizing a phosphorus oxyradical produced by γ -irradiation at room temperature in KDP and ADP crystals. A similar radical can be observed in pure BDP crystal γ -irradiated at room temperature. This radical could be the [PO5 ]2- or [O3POO]2-. MASD frequently crystallises in the β alum structure. The presence of the ClO4- ion in the growth solution induced the growth of α MASD crystals. The X-ray powder diffraction pattern and the EPR spectrum of the Cr3+ ions doped into α MASD are drastically different from those for the β MASD. The reasons for the inhomogeneous line broadening in α MASD and β MASD are different. Oxyradicals of Selenium and NH3+ radical are