High proton polarization in crystalline naphthalene by dynamic nuclear polarization with laser excitation at room temperature and liquid nitrogen temperature

Optimization of 1H spin density for dynamic nuclear polarization using photo-excited triplet electron spins

“…Also, the effect of spin-lattice relaxation restoring the spin system toward thermal equilibrium can be affected by the 1 H density. The buildup of 1 H polarization is determined by the balance of these competing factors, and its behavior is phenomenologically described by a differential equation [21] d dt…”

Proton polarization with p-terphenyl crystal by integrated solid effect on photoexcited triplet state

“…By monitoring the ESR signals, the direction of pentacene molecule could be adjusted. The way for the adjustment is similar to in the naphthalene experiments [13]. Typical linewidth of the ESR spectrum is about 30 G.…”

“…The experimental apparatus is the same as in the experiments with naphthalene crystals [13]. A synthesized sweep generator was used as a microwave source.…”

“…To improve the polarization in the crystalline naphthalene, we proposed that the crystal should be cooled down to temperature less than around 250 K, because a slow molecular motion, which is a dominant relaxation process in the naphthalene crystal, can be suppressed at temperature lower than around 250 K [13]. The relaxation rate around room temperature increases significantly with an increase in the laser power, because the relaxation due to the slow molecular motion is very sensitive to the temperature.…”

Spins in exotic nuclei: RI beam experiments with polarized targets

“…Although different lasers, an Ar-ion laser [51], a dye laser [57], and a disk laser [58] have been tested, none satisfies all the requirements. The RIKEN group has started to construct a new laser system which satisfies the requirements and fits best to the pentacene excitation.…”