The absorption spectra are reported for isolated Se andHgI2semiconductor chains accommodated inAlPO4-5 (AFI) channels of diameter 7.3 Å. The lowest electronic excitation states of the isolated chains are shifted to higher energy from the band edge transitions of their bulk crystals. The blue shifts are qualitatively explained by the quantum confinement effects of carriers in a one-dimensional wire. The experimental result of the Se/AFI is in good agreement with the theoretical expectation based on the effective-mass-approximation. The result of theHgI2/AFI, however, does not agree with the calculation. The different behaviors of the Se/AFI and theHgI2/AFI are expected to result from their different electronic structures. ©1997 American Institute of Physics.