Table 1 Calculated expression of Iedge for the forbidden Raman modes.

Correspondingly, a “yes” indicates that the mode is experimentally detected, while a “no” indicates that the mode is not experimentally detected. N/A, not applicable.

E1g mode of MoS2,
WS2, and WSe2
[ei, es]
[X, X][Y, Y][X, Y][Y, X]
Armchair (X)Iedge0d2iz2δsy2 + δiy2δsz2)d2δsz2d2δiz2
DetectedNoYesYesYes
Zigzag (Y)Iedged2iz2δsx2 + δix2δsz2)0d2δiz2d2δsz2
DetectedYesNoYesYes
B1g of BP[ei, es]
[X, X][Y, Y][X, Y][Y, X]
Armchair (X)Iedge0h2iz2δsy2 + δiy2δsz2)00
DetectedNoYesNoNo
Zigzag (Y)Iedge00h2δiz2h2δsz2
DetectedYes (weak)NoYesYes
B13g of BP[ei, es]
[X, X][Y, Y][X, Y][Y, X]
Armchair (X)Iedge00i2δsz2i2δiz2
DetectedNo0YesYes
Zigzag (Y)Iedgei2iz2δsx2 + δix2δsz2)000
DetectedYesNoNoNo
B23g of BP[ei, es]
[X, X][Y, Y][X, Y][Y, X]
Armchair (X)Iedge00j2δsz2j2δiz2
DetectedNoNoN/AN/A
Zigzag (Y)Iedgej2iz2δsx2 + δix2δsz2)000
DetectedYesNoN/AN/A