The surface structure of the prototypical topological insulator Bi2Se3 is determined by low-energy electron diffraction and surface X-ray diffraction at room temperature. Both approaches show that the crystal is terminated by an intact quintuple layer. Specifically, an alternative termination by a bismuth bilayer is ruled out. Surface relaxations obtained by both techniques are in good agreement with each other and found to be small. This includes the relaxation of the van der Waals gap between the first two quintuple layers.
@article{arxiv.1306.3310,
title = {Surface structure of Bi2Se3(111) determined by low-energy electron diffraction and surface X-ray diffraction},
author = {Diogo Duarte dos Reis and Lucas Barreto and Marco Bianchi and Guilherme Almeida Silva Ribeiro and Edmar Avellar Soares and Wendell Simoes e Silva and Vagner Eustaquio de Carvalho and Jonathan Rawle and Moritz Hoesch and Chris Nicklin and Willians Principe Fernandes and Jianli Mi and Bo Brummerstedt Iversen and Philip Hofmann},
journal= {arXiv preprint arXiv:1306.3310},
year = {2013}
}