TY  - JOUR
A1  - Mondal, Suvendu Sekhar
A1  - Kreuzer, Alex
A1  - Behrens, Karsten
A1  - Schütz, Gisela
A1  - Holdt, Hans-Jürgen
A1  - Hirscher, Michael
T1  - Systematic experimental study on quantum sieving of hydrogen isotopes in metal-amide-imidazolate frameworks with narrow 1-D channels
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - Quantum sieving of hydrogen isotopes is experimentally studied in isostructural hexagonal metal-organic frameworks having 1-D channels, named IFP-1, -3, -4 and -7. Inside the channels, different molecules or atoms restrict the channel diameter periodically with apertures larger (4.2 angstrom for IFP-1, 3.1 angstrom for IFP-3) and smaller (2.1 angstrom for IFP-7, 1.7 angstrom for IFP-4) than the kinetic diameter of hydrogen isotopes. From a geometrical point of view, no gas should penetrate into IFP-7 and IFP-4, but due to the thermally induced flexibility, so-called gate-opening effect of the apertures, penetration becomes possible with increasing temperature. Thermal desorption spectroscopy (TDS) measurements with pure H-2 or D-2 have been applied to study isotope adsorption. Further TDS experiments after exposure to an equimolar H-2/D-2 mixture allow to determine directly the selectivity of isotope separation by quantum sieving. IFP-7 shows a very low selectivity not higher than S=2. The selectivity of the materials with the smallest pore aperture IFP-4 has a constant value of S approximate to 2 for different exposure times and pressures, which can be explained by the 1-D channel structure. Due to the relatively small cavities between the apertures of IFP-4 and IFP-7, molecules in the channels cannot pass each other, which leads to a single-file filling. Therefore, no time dependence is observed, since the quantum sieving effect occurs only at the outermost pore aperture, resulting in a low separation selectivity.
KW  - gas adsorption
KW  - hydrogen isotopes
KW  - isotope separation
KW  - metal-organic frameworks
KW  - quantum sieving
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201900183
SN  - 1439-4235
SN  - 1439-7641
VL  - 20
IS  - 10
SP  - 1311
EP  - 1315
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - GEN
A1  - Wang, Xinxin
A1  - Huang, Xianyu
A1  - Sachse, Dirk
A1  - Ding, Weihua
A1  - Xue, Jiantao
T1  - Molecular paleoclimate reconstructions over the last 9 ka from a peat sequence in South China
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - To achieve a better understanding of Holocene climate change in the monsoon regions of China, we investigated the molecular distributions and carbon and hydrogen isotope compositions delta C-13 and delta D values) of long-chain n-alkanes in a peat core from the Shiwangutian SWGT) peatland, south China over the last 9 ka. By comparisons with other climate records, we found that the delta C-13 values of the long-chain n-alkanes can be a proxy for humidity, while the dD values of the long-chain n-alkanes primarily recorded the moisture source dD signal during 9-1.8 ka BP and responded to the dry climate during 1.8-0.3 ka BP. Together with the average chain length ACL) and the carbon preference index CPI) data, the climate evolution over last 9 ka in the SWGT peatland can be divided into three stages. During the first stage 9-5 ka BP), the delta C-13 values were depleted and CPI and Paq values were low, while ACL values were high. They reveal a period of warm and wet climate, which is regarded as the Holocene optimum. The second stage 5-1.8 ka BP) witnessed a shift to relatively cool and dry climate, as indicated by the more positive delta C-13 values and lower ACL values. During the third stage 1.8-0.3 ka BP), the delta C-13, delta D, CPI and Paq values showed marked increase and ACL values varied greatly, implying an abrupt change to cold and dry conditions. This climate pattern corresponds to the broad decline in Asian monsoon intensity through the latter part of the Holocene. Our results do not support a later Holocene optimum in south China as suggested by previous studies.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 543 
KW  - n-alkaline distributions
KW  - East-Asian monsoon
KW  - lacustrine sedimentary sequence
KW  - intertropical convergence zone
KW  - Western Nanling mountains
KW  - North-Atlantic climate
KW  - delta-D values
KW  - summer monsoon
KW  - isotopic composition
KW  - hydrogen isotopes
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-411608
SN  - 1866-8372
IS  - 543
ER  -