We propose to observe fundamental bands of CO and SiO in the
 infrared spectra of selected cool evolved stars by the highest
 resolution of the grating mode of ISO SWS. Our objective is to analyze
 the band structures of these molecules to clarify the physical
 structure of the upper atmosphere and inner circumstellar envelope of
 these stars. Understanding  the physical structure of the  upper
 photosphere-inner circumstellar boundary region  is of essential
 importance to resolve such critical problems as mass-loss mechanism,
 formation of circumstellar dust/molecules, excitation mechanism of
 stellar masers, etc., since  these phenomena mostly take place in the
 circumstellar envelope close to the stellar surface.
   The fundamental bands of CO and SiO may be the most important
 proves of the upper photosphere - chromosphere boundary, because of
 their high opacity. We hope to clarify the behaviour of CO and SiO
 fundamentals in the sequence of K-M giants and some supergiants, and
 further explore the changes of these bands during the pulsation of
 Mira variables. As we have already studied in some details the
 overtone bands of CO and SiO by the ground based high resolution
 spectra (see Sect.4), we hope to complete our analysis on the
 structure of the outer atmospheres of cool luminous stars with an
 analysis of the fundamental bands of CO and SiO using the unique
 possibility offered by the ISO. With the highest resolution possible
 by the SWS grating mode, we can resolve the band structures of
 CO and SiO (see Sect.3), and we hope to be able to extract some basic
 information on the physical conditions responsible to the formation
 of these bands.