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Multiple Photochemical Hole Burning in Tetraphenylporphine Derivatives Using a Focused Laser Beam

The recording properties of photochemical hole burning (PHB) in tetraphenylporphine (TPP) derivatives with a focused laser beam were studied. We demonstrated the possibility of more than 200-multiplicity recording in the frequency domain in tetrakis(pentafluorophenyl)porphine (TFP) in a 10-µm-diameter laser spot at 4 K. The effect of the laser irradiation time on the depth was also investigated using tetrakis(4-methoxyphenyl)porphine (TMP). Although the hole depth decreased with decreasing laser irradiation time down to the ms order due to the bottleneck effect (because of long triplet lifetime), a detectable hole is formed with irradiation by a 8 ms pulse using TMP.