Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 90% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 80% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 70% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 60% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 50% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 35% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 25% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-SWy-2 smectite saturated with H2O at RH19 Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SWy-2) under 5% relative humidity of H2O vapor