Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 90% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 80% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 70% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 60% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 50% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 35% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 25% relative humidity of H2O vapor Spectrum MIR ATR spectrum of Ca-exchanged montmorillonite (SCa-3) under 19% relative humidity of H2O vapor