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In order to investigate the chemical history of the entire MilkyWay, it isimperative to also study the dust-obscured regions, where most of the masslies. The Galactic Center is an example of such a region of interest, where dueto the intervening dust along the line-of-sight, near-infrared spectroscopicinvestigations are necessary. We demonstrate that M giants observed at highspectral resolution in the H and K bands (1.5-2.4 {\mu}m) can yield usefulabundance-ratio trends versus metallicity for 21 elements. These elements cantherefore be studied also for heavily dust-obscured regions of the Galaxy, suchas the Galactic Center, and will be important for the further investigation ofthe Galactic chemical evolution in these regions.  We have observed near-infrared spectra of 50 M giants in the solarneighbourhood at high SNR and at a high spectral resolution (R = 45, 000) withthe IGRINS spectrometer on the GEMINI South telescope. We adopted thefundamental stellar parameters for these stars from Nandakumar et al. (2023a),with Teff ranging from 3400 to 3800 K. With a manual spectral synthesis method,we have derived stellar abundances for 21 elements, namely F, Mg, Si, S, Ca,Na, Al, K, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Ce, Nd, and Yb. We demonstratewhat elements can be analysed from H- and K-band high-resolution spectra, andwe show which spectral lines can be used for abundance analysis, showing themline by line. We discuss the 21 abundance-ratio trends and compared them withthose determined from APOGEE and from the optical GILD sample. Especially, wedetermine the trends of the heavy elements Cu, Zn, Y, Ce, Nd, and Yb. Thisopens up these nucleosynthetic channels, including both the s- and ther-process, in dust-obscured populations. The [Mn/Fe] versus [Fe/H] trend isshown to be more or less flat at low metallicities, implying that existing NLTEcorrection are relevant.

M Giants with IGRINS III. Abundance Trends for 21 Elements in the Solar Neighborhood from High-Resolution, Near-Infrared Spectra