  There have been conflicting reports on the electronic properties of twin
domain boundaries (DBs) in MoSe2 monolayer, including the quantum well states,
charge density wave, and Tomonaga-Luttinger liquid (TLL). Here we employ
low-temperature scanning tunneling spectroscopy to reveal both the quantum
confinement effect and signatures of TLL in the one-dimensional DBs. The data
do not support the CDW at temperatures down to ~5 K.
