  The spectroscopic observations presented here were acquired during the 2017
August 21 total solar eclipse with a three-channel partially multiplexed
imaging spectrometer (3PAMIS) operating at extremely high orders ($>$ 50). The
4 $R_\odot$ extent of the slit in the North-South direction scanned the corona
starting from the central meridian out to approximately 1.0 $R_\odot$ off the
east limb throughout totality. The line widths and Doppler shifts of the Fe X
(637.4 nm) and Fe XIV (530.3 nm) emission lines, characteristic of $1.1 \times
10^6$ K and $1.8 \times 10^6$ K electron temperatures respectively, varied
across the different coronal structures intercepted by the slit. Fe XIV was the
dominant emission in the closed fields of an active region and the base of a
streamer, with relatively constant 20 - 30 km s$^{-1}$ line widths independent
of the height. In contrast, Fe X emission exhibited broader ($>40 $km s$^{-1}$)
line widths in open fields which increased with height, in particular in the
polar coronal hole. Inferences of line widths and Doppler shifts were
consistent with extreme ultraviolet (EUV) observations from Hinode/EIS, as well
as with the near-infrared Fe XIII 1074 nm line observed by CoMP. The
differences in the spectral line widths between distinct coronal structures are
interpreted as an indication of the predominance of wave heating in open
structures versus localized heating in closed structures. This study
underscores the unparalleled advantages and the enormous potential of TSE
spectroscopy in measuring line widths simultaneously in open and closed fields
at high altitudes, with minimal exposure times, stray light levels, and
instrumental widths.
