Water adsorption isotherms on CH3-, OH-, and COOH-terminated organic surfaces at ambient conditions measured with PM-RAIRS

Aimee Tu, Hye Rin Kwag, Anna L. Barnette, Seong H. Kim

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The water adsorption isotherms on methyl (CH3)-, hydroxyl (OH)-, and carboxylic acid (COOH)-terminated alkylthiol self-assembled monolayers (SAMs) on Au were studied at room temperature and ambient pressure with polarization modulation reflection-absorption infrared spectroscopy (PM-RAIRS). PM-RAIRS analysis showed that water does not adsorb at all on the CH 3-SAM/Au at subsaturation humidity conditions. In a dry Ar environment, the OH-SAM/Au holds at least 2 layer thick strongly bound water molecules which exhibit a broad O-H stretch vibration peak centered at ∼3360 cm-1. The peak position implies that the strongly bound water layer on the OH SAM is more like a liquid than an ice. The additional uptake of water in humid environments is relatively weak, and the peak position changes very little. Unlike the OH-SAM/Au, the COOH-SAM/Au does not have strongly bound water layer. This seems to be due to the strong hydrogen bonding between terminal COOH groups in dry conditions. The weak interactions between water and carboxyl groups at low relative humidity (RH) and the solvation of dissociated carboxylic groups in high RH lead to a type III isotherm behavior, based on the BET categories, for water adsorption on the COOH-SAM/Au. The water spectra on the COOH-SAM at RH > 45% are centered at ∼3430 cm-1 and very broad, indicating that the hydrogen-bonding network of water on the COOH-SAM is much different from that on the OH-SAM.

Original languageEnglish (US)
Pages (from-to)15263-15269
Number of pages7
JournalLangmuir
Volume28
Issue number43
DOIs
StatePublished - Oct 30 2012

Fingerprint

polarization modulation
Self assembled monolayers
Absorption spectroscopy
Adsorption isotherms
Infrared spectroscopy
absorption spectroscopy
isotherms
infrared spectroscopy
Modulation
Polarization
adsorption
Water
water
humidity
Atmospheric humidity
Hydrogen bonds
hydroxide ion
Solvation
Ice
carboxyl group

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

@article{d168896a708f43729b9514f7746a33fc,
title = "Water adsorption isotherms on CH3-, OH-, and COOH-terminated organic surfaces at ambient conditions measured with PM-RAIRS",
abstract = "The water adsorption isotherms on methyl (CH3)-, hydroxyl (OH)-, and carboxylic acid (COOH)-terminated alkylthiol self-assembled monolayers (SAMs) on Au were studied at room temperature and ambient pressure with polarization modulation reflection-absorption infrared spectroscopy (PM-RAIRS). PM-RAIRS analysis showed that water does not adsorb at all on the CH 3-SAM/Au at subsaturation humidity conditions. In a dry Ar environment, the OH-SAM/Au holds at least 2 layer thick strongly bound water molecules which exhibit a broad O-H stretch vibration peak centered at ∼3360 cm-1. The peak position implies that the strongly bound water layer on the OH SAM is more like a liquid than an ice. The additional uptake of water in humid environments is relatively weak, and the peak position changes very little. Unlike the OH-SAM/Au, the COOH-SAM/Au does not have strongly bound water layer. This seems to be due to the strong hydrogen bonding between terminal COOH groups in dry conditions. The weak interactions between water and carboxyl groups at low relative humidity (RH) and the solvation of dissociated carboxylic groups in high RH lead to a type III isotherm behavior, based on the BET categories, for water adsorption on the COOH-SAM/Au. The water spectra on the COOH-SAM at RH > 45{\%} are centered at ∼3430 cm-1 and very broad, indicating that the hydrogen-bonding network of water on the COOH-SAM is much different from that on the OH-SAM.",
author = "Aimee Tu and Kwag, {Hye Rin} and Barnette, {Anna L.} and Kim, {Seong H.}",
year = "2012",
month = "10",
day = "30",
doi = "10.1021/la302848k",
language = "English (US)",
volume = "28",
pages = "15263--15269",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "43",

}

Water adsorption isotherms on CH3-, OH-, and COOH-terminated organic surfaces at ambient conditions measured with PM-RAIRS. / Tu, Aimee; Kwag, Hye Rin; Barnette, Anna L.; Kim, Seong H.

In: Langmuir, Vol. 28, No. 43, 30.10.2012, p. 15263-15269.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Water adsorption isotherms on CH3-, OH-, and COOH-terminated organic surfaces at ambient conditions measured with PM-RAIRS

AU - Tu, Aimee

AU - Kwag, Hye Rin

AU - Barnette, Anna L.

AU - Kim, Seong H.

PY - 2012/10/30

Y1 - 2012/10/30

N2 - The water adsorption isotherms on methyl (CH3)-, hydroxyl (OH)-, and carboxylic acid (COOH)-terminated alkylthiol self-assembled monolayers (SAMs) on Au were studied at room temperature and ambient pressure with polarization modulation reflection-absorption infrared spectroscopy (PM-RAIRS). PM-RAIRS analysis showed that water does not adsorb at all on the CH 3-SAM/Au at subsaturation humidity conditions. In a dry Ar environment, the OH-SAM/Au holds at least 2 layer thick strongly bound water molecules which exhibit a broad O-H stretch vibration peak centered at ∼3360 cm-1. The peak position implies that the strongly bound water layer on the OH SAM is more like a liquid than an ice. The additional uptake of water in humid environments is relatively weak, and the peak position changes very little. Unlike the OH-SAM/Au, the COOH-SAM/Au does not have strongly bound water layer. This seems to be due to the strong hydrogen bonding between terminal COOH groups in dry conditions. The weak interactions between water and carboxyl groups at low relative humidity (RH) and the solvation of dissociated carboxylic groups in high RH lead to a type III isotherm behavior, based on the BET categories, for water adsorption on the COOH-SAM/Au. The water spectra on the COOH-SAM at RH > 45% are centered at ∼3430 cm-1 and very broad, indicating that the hydrogen-bonding network of water on the COOH-SAM is much different from that on the OH-SAM.

AB - The water adsorption isotherms on methyl (CH3)-, hydroxyl (OH)-, and carboxylic acid (COOH)-terminated alkylthiol self-assembled monolayers (SAMs) on Au were studied at room temperature and ambient pressure with polarization modulation reflection-absorption infrared spectroscopy (PM-RAIRS). PM-RAIRS analysis showed that water does not adsorb at all on the CH 3-SAM/Au at subsaturation humidity conditions. In a dry Ar environment, the OH-SAM/Au holds at least 2 layer thick strongly bound water molecules which exhibit a broad O-H stretch vibration peak centered at ∼3360 cm-1. The peak position implies that the strongly bound water layer on the OH SAM is more like a liquid than an ice. The additional uptake of water in humid environments is relatively weak, and the peak position changes very little. Unlike the OH-SAM/Au, the COOH-SAM/Au does not have strongly bound water layer. This seems to be due to the strong hydrogen bonding between terminal COOH groups in dry conditions. The weak interactions between water and carboxyl groups at low relative humidity (RH) and the solvation of dissociated carboxylic groups in high RH lead to a type III isotherm behavior, based on the BET categories, for water adsorption on the COOH-SAM/Au. The water spectra on the COOH-SAM at RH > 45% are centered at ∼3430 cm-1 and very broad, indicating that the hydrogen-bonding network of water on the COOH-SAM is much different from that on the OH-SAM.

UR - http://www.scopus.com/inward/record.url?scp=84868089772&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84868089772&partnerID=8YFLogxK

U2 - 10.1021/la302848k

DO - 10.1021/la302848k

M3 - Article

C2 - 23075312

AN - SCOPUS:84868089772

VL - 28

SP - 15263

EP - 15269

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 43

ER -