\( e^{x_{\small \kern-0.10em \mathsf{1}}} \)

\( e^{\lower0.2ex\hbox{$\scriptstyle x_1$}} \)

\( e^ {\kern-0.060em{\lower0.5ex\hbox{$\scriptstyle x_{\small\kern-0.20em 1}$}}} \)

\( e^{\kern-0.06em{\raise{-0.5ex}{\scriptstyle x_{\kern-0.20em 1}}}} \)

\( e^{\kern-0.06em{\raise{-0.5ex}{\scriptstyle x_{\small\kern-0.20em 1}}}} \)