Liu, RenhuiRenhuiLiuLi, Lin-HanLin-HanLiZhang, YeYeZhangHuang, JianqiJianqiHuangLin, Miao-LingMiao-LingLinTUAN HUNG NGUYENGuo, HuaihongHuaihongGuoWang, ZhenhuaZhenhuaWangZhang, ZhidongZhidongZhangSaito, RiichiroRiichiroSaitoTan, Ping-HengPing-HengTanYang, TengTengYang2025-12-182025-12-182025-08-1224699950https://www.scopus.com/record/display.uri?eid=2-s2.0-105021921273&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/734738Sixteen second-order Raman modes of monolayer MoSe2 are observed and analyzed by experiment and calculation, respectively, for four laser energies from 2.33–2.60 eV. The Raman peaks labeled by Pi (i = 1, 2, 3, 4) at 280–320 cm−1 and Si (i = 1, 2, 3) at 400–480 cm−1 are newly analyzed quantitatively by the first-principles calculation using QR2-CODE. The Pi bands are assigned to the second-order combination modes of TA (LA) and E'TO(E'LO), while the Si bands are assigned to the 2LA mode with different phonon wave vectors, which is explained by the combination of two-phonon density of states and electron-phonon coupling calculations. The overlapped Raman peak of the first-order mode E' and the second-order mode S1 can be identified separately using helicity-dependent Raman spectroscopy. The mode assignments are further confirmed by space-group analysis and helicity-dependent selection rule.falsejournal article10.1103/vvkp-9sth2-s2.0-105021921273