Spectrum MIR ATR spectrum of K-exchanged saponite under 80% relative humidity of D2O vapor Spectrum MIR ATR spectrum of K-exchanged saponite under 75% relative humidity of D2O vapor Spectrum MIR ATR spectrum of K-exchanged saponite under 70% relative humidity of D2O vapor Spectrum MIR ATR spectrum of K-exchanged saponite under 65% relative humidity of D2O vapor Spectrum MIR ATR spectrum of K-exchanged saponite under 60% relative humidity of D2O vapor