PROBLEM TO BE SOLVED: To provide an polarization source capable of stably transferring the spin polarization of an electron to the nucleus even in an environment having high oxygen tolerance and the presence of oxygen. SOLUTION: A polarization source of dynamic nuclear polarization composed of molecules represented by the following general formulas. 1 to 6 of Z1 to Z10 represent N, and the others independently represent CR. R represents a hydrogen atom or a substituent, and n represents an integer of 1 to 4. [Selection diagram] None【課題】酸素耐性が高く、酸素が存在する環境下においても、その電子のスピン偏極を安定に核へ移行できる偏極源を提供すること。【解決手段】下記一般式で表される分子からなる動的核偏極の偏極源。Ｚ１～Ｚ１０のうちの１～６個はＮを表し、その他は各々独立にＣ－Ｒを表す。Ｒは水素原子または置換基を表し、ｎは１～４の整数を表す。【選択図】なし
