  A vast amount of Raman spectroscopic data, obtained using diamond anvil cell
technique under in situ high pressure-temperature conditions, has been used for
mapping the phase transitions of hydrogen in the temperature range of 300 K to
900 K and pressure up to 300 gigapascal, a pressure-temperature region in which
most phase information was unknown previously. The isothermal and isobaric
dependencies in frequency and peak width for intramolecular vibration Raman
mode of hydrogen are established based on thousands of data files which are
measured during hundreds of independent high pressure-temperature experimental
runs. Discontinuities of pressure and temperature dependencies in frequency and
peak-width, together with appearance or disappearance of observed Raman modes
were obtained. Those transition data show self-consistency and have been used
for outlining 13 phase transition boundaries and 15 possible phases. This
large, diversified behavior of spectra demonstrates that surprisingly rich and
complicated phase transitions may exist in this pressure-temperature region.
