A nanoparticle for a photochromic material, generation of hydrated electrons, or decomposition of a halogen-containing organic material, the nanoparticle comprising a nanoparticle that comprises an organic ligand represented by the following Formula (2′) on the surface of a particle represented by the following Formula (1′):
- [in Formula (1′), X represents a Group 16 element]
- [in Formula (2′), Y is selected from OCO, OSO2, OSO, and SCS—N(R23);
- R21 represents an organic group having 1 to 20 carbon atoms that is optionally substituted with SH or fluorine;
- R22 represents H, F, COOH, or NH2;
- and R23 represents a monovalent organic group having 1 to 20 carbon atoms that is optionally substituted with SH or fluorine].