Loschmidt constant
（重定向自Loschmidt Number）
The Loschmidt constant or Loschmidt's number (symbol: n0) is the number of particles (atoms or molecules) of an ideal gas in a given volume (the number density). It is usually quoted at standard temperature and pressure, the 2010 CODATA recommended value is 2.686 7805(24)×10 per cubic metre at 0 °C and 1 atm and the 2006 CODATA recommended value was 2.686 7774(47)×10 per cubic metre at 0 °C and 1 atm. It is named after the Austrian physicist Johann Josef Loschmidt, who was the first to estimate the physical size of molecules in 1865. The term "Loschmidt constant" is also sometimes used to refer to the Avogadro constant, particularly in German texts.