Development and validation of Ni–Ni electrolytic enrichment method for tritium determination in samples of underground waters of Jeju Island

A method of tritium electrolytic enrichment was developed, optimized and validated. The enrichment parameters were compared with different current and total current charge variation and tritium separation factor was from 8 to 36 with a current density variation. The detection limit of tritium measurement is about 0.5 TU using 1,000 mL sample and 600 min counting time. Several samples of groundwaters were processed in our and another laboratory with good agreement of results within 15% deviation. Developed and validated method of tritium determination was applied groundwaters in Jeju Island with a liquid scintillation counter (LSC) and electrolytic enrichment method using Ni–Ni electrodes. The tritium concentrations in fifty eight groundwaters in Jeju Island were ranged <0.5 TU-3.9 TU and averaged value was 2.12 TU.     

Tritium measurement in the Western Caucasus

Measurement of tritium in water of rains, springs, wells, mud volcanoes and rivers, lakes of the Western Caucasus (Krasnodar region) has been carried out since 1997 for hydrogeology, engineering geology, ecology and seismology. Electrolytic cells with spiral electrodes and the big multiwire proportional chamber were used for low tritium concentration measurements on expeditions. With the new design of the cell the enrichment factor of 64.0 ± 1.5 % was obtained during the electrolytic process. Correlation of tritium concentration is observed in mud volcanoes and spring water with regional seismicity. The long-term tritium data are shown in natural waters in South Russia.     

Efficiency of tritium enrichment by electrolytic cell with multi-nickel-plates electrode and its application to the determination of tritium in environmental water

For the purpose of speeding up the tritium enrichment by electrolysis, we have produced an electrolytic cell with the multi-plate-electrode system instead of the commonly used single-plate-electrode, and examined the efficiencies for the tritium enrichment under the conditions of different current densities and electrode gaps. From the results, the tritium recovery and the separation factor beta were found to be maximized under the condition of 70 mA/cm2 of current density and 1.6 mm of electrode gap, and they were 90 percent and 23, respectively. Using this cell, it took 28 hours to reduce 100 ml of a sample water to 10 ml, and took 2 days, including the time required for other operations, to determine the tritium concentration of 1.85 Bq/l (50 pCi/l) with the counting error of within +/- 10 percent. This method has been applied to determining the tritium concentrations of environmental samples from Yamato River region during July 1981-February 1983. They were in the range of 1.11-9.48 Bq/l (30-256 pCi/l).     

Determination of tritium in water using electrolytic enrichment: methodology improvements

The quality control of the method for tritium (³H) determination in water after electrolytic concentration by liquid scintillation counting measurements was improved considering more parameters in the uncertainty budget, besides the control charts to evaluate the electrolytic enrichment factor, the enrichment parameter and blank samples. The quality control upgrade of the method and the participation in proficiency tests allow its optimization. This methodology was applied to the determination of ³H activity concentrations in waters from different origins: surface, rain and drinking waters.     

Tritium in surface waters, tap water and in precipitation in Poland during the 1994–1999 period

Concentrations of tritium in environmental waters (precipitation, rivers, lakes, tap water) have been determined using electrolytic enrichment and liquid scintillation counting. In waters of big rivers (the Vistula and the Odra rivers), lakes and tap water the annual average concentrations were similar to each other being from 1.4 to 1.9 Bq·dm^-3. These concentrations were similar to those in the precipitation in which they ranged from 1.7 to 2.2 Bq·dm^-3. The lowest tritium concentrations were found in waters of the Seashore Region rivers (average for 1994–1999 was 1.1 Bq·dm^-3). The tritium concentrations in surface waters and in precipitation are still higher than that of natural level. The data obtained show that tritium concentration in the water of rivers might depend on the size of drainage area. The observed seasonal variations of tritium concentration in the precipitation collected in Warsaw and at the Mount Sniezka indicate the stratospheric source of tritium. It was found that about 30% of tritium deposited with precipitation is removed to the Baltic Sea with river waters.     

A method for the determination of tritium in environmental water samples by electrolytic enrichment

In order to determine the tritium concentration in environmental water samples, the electrolytic enrichment was carried out with (St) and without (S) addition of tritiated water of a certain concentration (deuterium-free) to the samples. With the use of the fundamental formulas on electrolytic enrichment, the deuterium concentration (Dit) before electrolysis for an environmental water sample is determined by liquid scintillation counting and densitometry for the sample St. Furthermore, the tritium concentration in the environmental water sample is determined by the above methods for the sample S, and by the substitution of Dit for Di in the formulas. Tritium concentrations in environmental water samples were found to be determined within an accuracy of 10% by this method when Vi/Vf was 14-25. It is considered that this method dispenses with the direct measurement of low deuterium concentrations (Di) before electrolysis, a special technique on the purification of water for densitometry, and moreover, excludes the possibility of cross contamination in the electrolytic enrichment by the spike cell method.     

CRYSTAL STRUCTURE OF 6-ETHOXY-5,6-QIHYDROCHELERYTHRINE

<正> C23H23O5N Mr = 393.44, triclinic,space group P 1, a =7.659(3), b= 10.183(10), c=13.396(2)A,α=92.21(7),β=100.86(2),γ=108.16(7)°,Z=2.The structure was solved by direct methods and refined to a final R factor of 0.055, Rw=0.050). The title compound belongs to the alkaloid of benzoheterophenanthrene, the molecule possesses two conjugation planes which are proped up by N(5)-C(6) bond and the dihedral angle is 12.74(24)°.     

CRYSTAL STRUCTURE OF 2-(PHENYLAMINO THIOFORMYD-3,4,5,6-TETRAHYDROPYRIMIDINE

<正> The title compound 2-(phenylamino thioformyl)-3,4,5,6-tetrahy-dropyrimidine(C11H13N3S,Mr=219)was synthesized by the reaction of N,N'-diphenyl dithiooxamide with 1,3-diamine trimethylene.The crystal is monoclinic,space group P21,with unit cell constants a=6.253(1),b=7.304(1),c=12.027(2)A,β=102.71(1)°,Z=2,V=535.9(2)A3,Dc=1.35.g/cm3.The final deviation factor R=0.025.The result reveals that the dihedral angle between the thio-formyl group [S,C(7),C(8),N(1)]and the phenyl ring is 33.4°,and the thio-formyl group and the mean plane of the atoms [N(3),C(8),N(2),C(9)]are nearly coplanar.     

CRYSTAL AND MOLECULAR STRUCTURE OF 1-PHENYLAMINOMETHYL-3,7,10-TRIMETHYL-2,8,9-TRIOXA-5-AZA-1-SILITRICYCLO(3,3,3,0~(1,5)) UNDECANE

<正> The transparent colourless crystal of the title compound crystallized in monoclinic system with space group P21/c and cell dimensions a=9.857(7), b=11.128(4), c=16.036(7) A, β=103.31(5)°, V=1711.7A3, Z=4, Dc= 1.25 g.cm-3, λ =-1.5418 A, μ= 13.067 cm-1. The structure was solved by direct methods and refined by full matrix least-squares, the final discrepancy factor R=0.061 and Rw=0.060. The skeleton of the molecule is composed of three five-membered rings with a common edge N(l)-Si(l), and the dihedral angles between each two of the three rings are 110.5°, 107.9° and 105.0° respectively. The N(l)-Si(l) coordination bond length is 2.143(3) A. In comparison with the structures of other related compounds, it was found the N-Si bond length varies with the electronegativities of the substitute groups R at Si atom.     

Determination of low-level tritium concentrations in surface water and precipitation in the Czech Republic

Past tests of nuclear weapons in the atmosphere, nuclear energy facilities and tritium of natural origin are main sources of tritium in the environment. Thanks to its presence in environment and its favourable properties, tritium is used as a radiotracer. Since stopping of atmospheric nuclear tests, tritium in precipitation has been decreasing towards natural levels below 1 Bq l^?1 and precise analyses of low level tritium activities are necessary. This paper focuses on tritium development at sites not influenced by any technogenic release of tritium in Elbe River basin (Bohemia) in the Czech Republic using liquid scintillation measurement with electrolytic enrichment.     

2 + 3] cycloaddition of nitrones to platinum-bound organonitriles: effect of metal oxidation state and of nitrile substituent

The ligated benzonitriles in the platinum(II) complex [PtCl2(PhCN)2] undergo metal-mediated [2 + 3] cycloaddition with nitrones -ON+(R3)=C(R1)(R2) [R1/R2/R3 = H/Ph/Me, H/p-MeC6H4/Me, H/Ph/CH2Ph] to give delta 4-1,2,4-oxadiazoline complexes, [PtCl2(N=C(Ph)O-N(R3)-C(R1)(R2))2] (2a, 4a, 6a), as a 1:1 mixture of two diastereoisomers, in 60-75% yields, while [PtCl2(MeCN)2] is inactive toward the addition. However, a strong activation of acetonitrile was reached by application of the platinum(IV) complex [PtCl4(MeCN)2] and both [PtCl4(RCN)2] (R = Me, Ph) react smoothly with various nitrones to give [PtCl4(N=C(R)O-N(R3)-C(R1)(R2))2] (1b-6b). The latter were reduced to the corresponding platinum(II) complexes [PtCl2(N=C(R)O-N(R3)-C(R1)(R2))2] (1a-6a) by treatment with PhCH2NHOH, while the reverse reaction, i.e. conversion of 1a-6a to 1b-6b, was achieved by chlorination with Cl2. The diastereoisomers of [PtCl2(N=C(R)O-N(R3)-C(R1)(R2))2] (1a-6a) exhibit different kinetic labilities, and liberation of the delta 4-1,2,4-oxadiazolines by substitution with 1,2-bis(diphenylphosphino)ethane (dppe) in CDCl3 proceeds at different reaction rates to give free N=C(R)O-N(R3)-C(R1)(R2) and [PtCl2(dppe)] in almost quantitative NMR yield. All prepared compounds were characterized by elemental analyses, FAB mass spectrometry, and IR and 1H, 13C(1H), and 195Pt (metal complexes) NMR spectroscopies; X-ray structure determination of the first (delta 4-1,2,4-oxadiazoline)Pt(II) complexes was performed for (S,S)/(R,R)-rac-[PtCl2(N=C(Me)O-N(Me)-C(H)Ph)2] (1a) (a = 9.3562(4), b = 9.8046(3), c = 13.1146(5) A; alpha = 76.155(2), beta = 83.421(2), gamma = 73.285(2) degrees; V = 1117.39(7) A3; triclinic, P1, Z = 2), (R,S)-meso-[PtCl2(N=C(Ph)O-N(Me)-C(H)Ph)2] (2a) (a = 8.9689(9), b = 9.1365(5), c = 10.1846(10) A; alpha = 64.328(6), beta = 72.532(4), gamma = 67.744(6) degrees; V = 686.82(11) A3; triclinic, P1, Z = 1), (S,S)/(R,R)-rac-[PtCl2(N=C(Me)O-N(Me)-C(H)(p-C6H4Me))2] (3a) (a = 11.6378(2), b = 19.0767(7), c = 11.5782(4) A; beta = 111.062(2) degrees; V = 2398.76(13) A3; monoclinic, P2(1)/c, Z = 4), and (S,S)/(R,R)-rac-[PtCl2(N=C(Me)O-N(CH2Ph)-C(H)Ph2] (5a) (a = 10.664(2), b = 10.879(2), c = 14.388(3) A; alpha = 73.11(3), beta = 78.30(3), gamma = 88.88(3) degrees; V = 1562.6(6) A3; triclinic, P1, Z = 2).     

Experimental and Theoretical Investigations of the Formation of the Diazene PhSN=C(H)N=NC(H)=NSPh from HCN(2)(SPh)(3) by a Thiyl-Radical-Catalyzed Mechanism: Identification of the HC(NSPh)(2)(*) Radical and X-ray Structures of HCN(2)(SPh)(3) and PhSN=C(H)N=NC(H)=NSPh

The reaction of HCN(2)(SiMe(3))(3) with benzenesulfenyl chloride in a 1:3 molar ratio produces HCN(2)(SPh)(3) (4) as thermally unstable, colorless crystals. The decomposition of (4) in toluene at 95 degrees C was monitored by UV-visible, (1)H NMR and ESR spectroscopy. The major final products of the decomposition were identified as PhSN=C(H)N=NC(H)=NSPh (5) and PhSSPh. The structures of 4 and 5 were determined by X-ray crystallography. The crystals of 4 are monoclinic, space group P2(1)/a, with a = 9.874(2) ?, b = 19.133(2) ?, c = 10.280(2) ?, beta = 113.37(1) degrees, V = 1782.8(5) ?(3), and Z = 4. The final R and R(w) values were 0.042 and 0.049, respectively. The crystals of 5 are monoclinic, space group P2(1)/n, with a = 5.897(6) ?, b = 18.458(10) ?, c = 7.050(8) ?, beta = 110.97(5) degrees, V = 716(1) ?(3), and Z = 2. The final R and R(w) values were 0.075 and 0.085, respectively. The diazene 5 adopts a Z,E,Z structure with weak intramolecular S.N contacts of 2.83 ?, giving rise to four-membered NCNS rings. During the thermolysis of 4 at 95 degrees C in toluene a transient species (lambda(max) 820 nm) was detected. It decomposes with second-order kinetics to give 5 (lambda(max) 450 nm). The ESR spectrum of the reaction mixture consisted of the superposition of a three-line 1:1:1 spectrum (g = 2.0074, A(N) = 11.45 G), attributed to (PhS)(2)N(*), upon a doublet of quintets (1:2:3:2:1) with g = 2.0070, A(N) = 6.14 G, A(H) = 2.1 G assigned to the radical HCN(2)(SPh)(2)(*). Density functional theory (DFT) calculations for the models of the radical showed the E,Z isomer to have the lowest energy. Thermochemical calculations indicate that the decomposition of HCN(2)(SH)(3) into the diazene (Z,E,Z)-HSN=C(H)N=NC(H)=NSH (and 2 HSSH) is substantially more exothermic (DeltaH = -176.1 kJ mol(-)(1)) than the corresponding formation of the isomeric eight-membered ring (HC)(2)N(4)(SH)(2) (DeltaH = -40.6 kJ mol(-)(1)). These calculations also indicate that the diazene is formed by a mechanism in which the RS(*) radical acts as a catalyst.     

Crystal Structure of N-Phenylisothiocyanatido-Phosphonamidothioate

1INTRODUCTIONLawess0n,Sreagent(LR),2,4-Bis(4-meth0xyphenyl)-1,3,2'4-dithiadiphosphetane-2,4-disulfide,notonlyisaselectivereagentf0rthi0natingcar-bonylcompounds,buta1soreactswithcertainsubstratestogivephosph0rushetero-cyclecompoundswhichcontainthe(4-methoxyphenyl)phosphinothi0ylidene"4-CH,OC,H'P(S)"m0iety.Theseheterocycliccompoundshavesomepotentialbiologi-calactivitiesasherbicides,fungicides,andinsecticides[l'2J.Wehavestudiedthecy-clizationofthebifunctionalsubstrateswithLRtogive5-and6…     

Finite size scaling for the atomic Shannon-information entropy

We have developed the finite size scaling method to treat the criticality of Shannon-information entropy for any given quantum Hamiltonian. This approach gives very accurate results for the critical parameters by using a systematic expansion in a finite basis set. To illustrate this approach we present a study to estimate the critical exponents of the Shannon-information entropy S approximately (lambda-lambda(c))(alpha(S) ), the electronic energy E approximately (lambda-lambda(c))(alpha(E) ), and the correlation length xi approximately mid R:lambda-lambda(c)mid R:(-nu) for atoms with the variable lambda=1/Z, which is the inverse of the nuclear charge Z. This was realized by approximating the multielectron atomic Hamiltonian with a one-electron model Hamiltonian. This model is very accurate for describing the electronic structure of the atoms near their critical points. For several atoms in their ground electronic states, we have found that the critical exponents (alpha(E),nu,alpha(S)) for He (Z=2), C (Z=6), N (Z=7), F (Z=9), and Ne (Z=10), respectively, are (1, 0, 0). At the critical points lambda(c)=1/Z(c), the bound state energies become absorbed or degenerate with continuum states and the entropies reach their maximum values, indicating a maximal delocalization of the electronic wave function.     

Crystal and molecular structure of dimethyl 4-phenyl-S-methylisothiosemicarbazide diacetate and its complex with copper(II) bromide

The structure of dimethyl 4-phenyl-S-methylisothiosemicarbazide diacetate NH(C₆H₅)C(SCH₃)NN × (CH₂COOCH₃)₂ (Z) hydroiodide (I) (crystals I are triclinic, space group $P\bar 1$ , a=11.671(3), b=10.889(2), c=8.237(2) Å,α=78.59(2),β=77.63(2),γ=106.47(2)°, Z=2, final R=0.088) and a complex of Z with copper(II) bromide, CuBr₂Z (II) (crystals II are orthorhombic, space group Pbca, a=14.487(4), b=18.827(8), c=14.565(5) Å, Z=8, R=0.062) was determined by X-ray diffraction analysis. It is established that methylation of the sulfur atom changes the type of ligand attachment to the metal, namely, the ligand is transformed from the tripod S,N,O,O, into the N,N,O,O type (the sulfur atom is not involved in coordination). When coordinated, the ligand does not change conformation, and the thiosemicarbazide fragment retains the E-configuration. During complexation, Z topologically behaves as a classical complexon of the monoamine series.     

钼铁硫原子簇化合物的合成与结构化学研究II: 以Fe(SR)6为桥的双类立方烷化合物的合成及(Et4N)4[Mo2Fe7S8(SC6H4CH3-m)12].2THF的晶体结构

在乙腈溶液中(Et4N)2[Fe4(SR)10]与(Et4N)2[MoS4]反应半小时生成对氧极为敏感的系列黑色晶状化合物(Et4N)4[Mo2Fe7S8(SR)12](R=C6H5,1;R=C6H4CH3-m, 2;R=C6H4CH3-o, 3;R=C6H4CH3-ρ,4). 2.2THF晶体的分子量为2982.8, 属单斜晶系;空间群为P21/n; a=18.022(2), b=18.375(2), c=22.254(3)A; β=71.04(1)°;V=6969(2)A^3;Dc=1.424g.cm^-^3;Z=2;F(000)=3108.晶体结构用直接法解出,修正至R=0.064. 2.2THF中Mo...Mo'距离为7.234A.     

Tritium content as indicator of environmental character on Taiwan Island

Environmental characters have been established by tritium contents in well water, coastal seawater and reservoir water collected from various places around Taiwan island. Tritium concentrations of samples were detected by a liquid scintillation analyzer TRI-CARB-LSC 2550 TR mode, with a low level standard quench curve. After samples were concentrated by electrolysis, tritium concentration was detected in optimum conditions of LLLSA. An electrolytic enrichment technique was also developed with a eurrent density of 100 mA/cm² and 0.4–0.6% (Na₂O₂) electrolyte in concentrated samples. Data observed show a lower tritium concentration for coastal seawater than for wells in the same area. The tritium concentration ratio of well and coastal seawater on the western side of Taiwan is 4.000 and on the eastern side 5.801. Tritium content of reservoir water is related to the logarithm of effective volume capacity.     

Electrocrystallization of Tetra‐ and Hexa‐coordinated Silver(II) Compounds Based on 4,4′‐Dimethyl‐2,2′‐Bipyridine Ligand – Single Crystal Structures and Magnetic Studies

In this paper we report on the potential dependent electrocrystallization of [Ag(4,4′‐dimethyl‐2,2′‐bipyridine)₂(NO₃)₂] ( 1 ) and Ag(4,4′‐dimethyl‐2,2′‐bipyridine)(NO₃)₂ ( 2 ) from the same electrolytic bath. Thus it has been shown for the first time that the coordination number of silver ion to ligands can be tuned by the electrocrystallization potential. The single crystal structure analysis [ 1 : C2/c, a = 18.6308(15), b = 14.5708(12), c = 11.5867(10) Å, β = 126.5910(10)°, Z = 4, R = 3.9 %] [ 2 : P2₁/c, a = 8.5865(11) b = 11.0157(14) c = 16.4554(10) Å, β = 111.102(10), Z = 4 , R = 3.5 %] show divalent silver to be in an approximately square planar surrounding. Both complexes are paramagnetic following Curie's law with magnetic moments of 1.86 μ_B and 1.72 μ_B respectively.     

Lanthanide chalcogenolate complexes: synthesis and crystal structures of the isoleptic series [Sm(TpMe,Me)2ER] (E = O, S, Se, Te; TpMe,Me = tris-3,5-dimethylpyrazolylborate)

A series of lanthanide complexes containing a chalcogenolate ligand supported by two TpMe,Me (tris-3,5-dimethylpyrazolylborate) groups has been prepared and crystallized and provides direct comparisons of bonding to hard and soft ligands at lanthanide centers. Reaction of [Sm(TpMe,Me)2Cl] with NaOR (R = Ph, Ph-Bu(t)) gives [Sm(TpMe,Me)2OR] (1a and 1b, respectively) in good yields. Reductive cleavage of dichalcogenides by samarium(II) was used to prepare the heavier congeners. Complexes of the type [Sm(TpMe,Me)2ER] for E = S, R = Ph (2a), E = S, R = Ph-4-Me (2b), E = S, R = CH2Ph (2c), E = Se, R = Ph (3a), E = Se, R = Ph-4-Bu(t) (3b), E = Se, R = CH2Ph (3c), and E = Te, R = Ph (4) have been prepared together with the corresponding complexes with TpMe,Me,4-Et as ancillary. The X-ray crystal structures of 1b, 2b, 3a, 3b, and 4 have been determined. The crystal of 1b (C40H57B2N12OSm.C7H8) was monoclinic, P2(1)/c, a = 10.6845(6) A, b = 18.5573(11) A, c = 24.4075(14) A, beta = 91.616(2) degrees, Z = 4. The crystal of 2b (C37H51B2N12SSm) was monoclinic, P2(1)/n, a = 15.0154(9) A, b = 13.1853(8) A, c = 21.1254(13) A, beta = 108.628(2) degrees, Z = 4. The crystal of 3a (C36H49B2N12SeSm.C7H8) was triclinic, P1, a = 10.7819(6) A, b = 19.3011(10) A, c = 23.0235(12) A, alpha = 79.443(2) degrees, beta = 77.428(2) degrees, gamma = 89.827(2) degrees, Z = 4. The crystal of 3b (C40H57B2N12SeSm) was triclinic, P1, a = 10.1801(6) A, b = 10.2622(6) A, c = 23.4367(14) A, alpha = 88.313(2) degrees, beta = 86.268(2) degrees, gamma = 62.503(2) degrees, Z = 2. The crystal of 4 (C36H49B2N12TeSm.C7H8) was monoclinic, P2(1)/c, a = 18.7440(10) A, b = 10.3892(6) A, c = 23.8351(13) A, beta = 94.854(2) degrees, Z = 4. The compounds form an isoleptic series of seven-coordinate complexes with terminal chalcogenolate ligands. Examination of 1b and other crystallographically characterized lanthanide alkoxides suggests that there is little correlation between bond angle and bond length. The structures of 3a and 3b, however, contain molecules in which one of the pyrazolylborate ligands undergoes a major distortion arising from twisting around a B-N bond so as to give an effectively eight-coordinate complex with pi-stacking of the phenyl group with one pyrazolyl ring. These distortions shed light on the fluxionality of these systems.     

Copper(I) complexes of tripodal tris(imidazolyl) ligands: potential mimics of the Cu(A) site of hydroxylase enzymes

Copper(I) complexes of tripodal tris(N-methyl-4,5-diphenyl-imidazolyl)methane ligands, N3CR (1a-c, R = OH, OMe, H), have been prepared as models for the Cu(A) site of copper hydroxylase enzymes. In the absence of additional donors, the ligands 1 react with [Cu(CH3CN)4]PF6 (2) to produce dinuclear complexes [(N3CR)2Cu2](PF6)2 (3) in which the tripodal ligands bridge two trigonal Cu centers; the structures of 3b and 3c are established by X-ray diffraction. Mononuclear adducts [(N3CR)CuL]Z are produced with L = acetonitrile (4), carbon monoxide (5), and t-BuNC (6, 7). The carbonyl complexes 5 are in dynamic equilibrium with the dimeric complexes 3, but 5c (R = H) can be isolated. The structures of the isocyanide derivatives depend critically on the tripod methane substituent, R. Thus, the X-ray structures of 6 (R = OMe) and 7 (R = H) show trigonal and tetrahedral geometries, respectively, with bi- or tridentate coordination of the tripod. A trinuclear complex [Cu3(N3COH)2(t-BuNC)2](PF6)3 (8) is formed from N3COH (1a) which features both three-coordinate and two-coordinate Cu atoms and bidentate tripod coordination. Reactions of dioxygen with dinuclear 3c or mononuclear [(N3CR)CuL]Z are sluggish, producing from the latter in acetone [(N3CH)CuII(L)(L')](PF6)2 (9, L = acetone, L' = H2O).