Program: GS-2008A-C-2

\hspace{0.4 in} We have recently discovered long column lengths of high temperature ($T$ $\sim$ 250 K) and low density ($n$ $\sim$ 100 cm$^{-3}$) gas with a large velocity dispersion in the Central Molecular Zone (CMZ), a region near the Galactic center (GC) with a radius of $\sim$ 200 pc. This is a new category of interstellar environment in the Galactic center, in addition to the three previously reported, i.e., the dense and mostly cold molecular clouds observed by radio emission, the hot ($\sim$ 10$^{4-6}$ K) highly ionized gas ($n_e$ $\sim$ 10--100 cm$^{-3}$) observed by atomic fine structure spectra and inferred from hyper-strong radio-wave scattering, and the ultra-hot ($\sim$ 10$^{7-8}$ K) X-ray emitting plasma gas. \hspace{0.4 in} We here propose to extend our observation to wider regions of the CMZ to obtain a larger picture of the newly found gas. Sightlines toward eight bright infrared sources within $\sim$ 30 pc of the GC will be studied. Four of them have been observed at lower resolution and with lower sensitivity, and higher quality spectra from the Phoenix Spectrometer are indispensable to obtain more definitive information. The observations will provide information on temperature, density, the local ionization rate $\zeta$, and radial lengths of clouds, that are important astrophysical quantities for understanding the extraordinary activity in the Galactic center.