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Updated: Mar 31, 2026

Dissection and 2-Photon Imaging of Peripheral Lymph Nodes in Mice
Published on: August 23, 2007
Mechanism of two-photon excited hemoglobin fluorescence emission
Qiqi Sun1, Wei Zheng2, Jiannong Wang3
1Hong Kong University of Science and Technology, Department of Electronic and Computer Engineering, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Abstract:
Hemoglobin, one of the most important proteins in the human body, is composed of “heme” groups (iron-containing rings) and “globins” (proteins). We investigate the two-photon excited fluorescence of hemoglobin and its subunit components (heme and globin). We measure the hemoglobin fluorescence lifetime by using a streak camera of ps resolution and confirm that its lifetime is in femtosecond scale. In the study of the fluorescence properties of heme and globin, the experimental results reveal that heme is the sole fluorophore of hemoglobin. Hemoglobin fluorescence can be effectively excited only via two-photon process, because heme has a centrosymmetric molecular structure and two-photon allowed transition is forbidden for single-photon process and vice versa due to the Laporte parity selection rule.
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