quencp is known to he sensitive to the electroiiir environment of a carboxylate ion. For instance, Kagarisei4 has showii for the salts of phenylstearic acid that a linear relationship exists betvieen the nntisymmetric COO stretching frequency and the electronegativity of the metal constituent of the molecule. ,'lccordingly, if the two-dimensional network structure as suggested by magnetic measurements is present in the crystals of some copper(11) a,@-dicarboxglntes, it is expected that the antisymmetric COO stretching frequency is shifted to some extent from its normal position, JThicli may he presumed to be represented by the corresponding frequency observed for sodium salts. Table I1 gives the antisymmetric COO stretching frequencies observed for both copper(I1) and sodium salts of various cup-dicarboxylic acids. If the difference between the COO frequencies of the coppcr(I1) and sodium salts, 1% hich differeiicc is practicdly zero for ropper(I1) nialonate showing a normal magnetic moment, is plotted against the number of ciarhon atoms in an acid radical, the graph hears a fairly close resemblance in shape to that of the magnetic moment of the copper(J1) salts per one copper atom plotted against the same ab3cis-a.1 In other n-ords, the dependence of the shift of the antisymmetric COO stretching frequency of the copper(I1) salts from the normal (14) R . J
I < a y a ~ i w Trrw , J o I ' R \ ~ I
59 271 (195.5)
n
2 3 3 5 ti r (
8 I)
10
cu salt 1665 1595 1608 I590 I d82 I592 1595 I S95 1.595
position is similar t o that of thc devintion of the magnetic moment of the copper(I1) salts from the theoretical spin-only moment for oiie odd electron. This striking parallelism in these two quantities suggests that wherever the truth lies in this debatable problem, there can be no doubt that these two quantities are intimately related to each other and have their origin in common. Presumably, the electronic structure about a copper atom or n pair of copper atoms is responsihle Tor the similadependence of the two quantities npon the niinir her of carbon atom3 in the acid radical
A ST14SD_ATIDFLUORESCESCE SPECTRTJJI FOR CL41,1BR14TTSG SPF,CTRO-FLCORC)PHOTO~~~T~I~S BY IT. H. NELHUISH Contribxtion
,\'TO. 7 3 from
the Instztirte
o.f
n'?rclwr Sciences, Department of ScienliJic nnd Tnditstrid Reseatrh, J1oiocr Hictt, ,YPW Zealand R e c e v ~d December 14. 1959
The energy and quantum fluorescence spectrum of quinine bisulfate in S H26O4has bern nieasiirrd. Thc energy a t each wave length (joules sec -l cm.-l mp-1) was determined by comparison with a tungsten lamp of known color trmperature. The quinine bisulfate fluorescence spectrum is proposed as a stantfard for ca1ibr:rting monochromators to he used for measuring fluorescence or phosphorescence spectra.
Introduction Fluorwcence spectra have important applica t ions ' in physical chemistry especially in such studies as fluorescence quenching, transfer of electronic excitation energy between molecules, the measurement of fluorescence efficiencies and in fluorescence analysis. Previous workers have measured fluorescence qpectra t)y visual, photographic or photoelectric methods. The ohserved spectrum was usually compared with the spectrum of a tungsten lamp of known color temperature ineawred in the same apparatus, to obtain the relative energy or number of quanta emitted at each wave length. The energy or quanta emitted by the filament at different wave lengths mas either measured with a thermopile or calculated from Planck's law (or Wien's law if extreme accuracy was not required). In order to avoid the necessity of calibrating the monochromator with a tungsten lamp, Kortum and Finckh' suggested that the fluorescence spec-
trum of quinine sulfate in M H,S04 he used as n transfer standard. Thew authors d c l ermined the energy fluorescence spectrum of quinine wlfate hy a photographic method and obtained the spect rum shown in Fig. 1. Work in this Laboratory has thrown some doubt on the correctness of the spectrum published by Kortum and Finckh. The quantum fliiorescence qpectrum of anthracene in benzene given hy llelhuish2 was determined with a Beckman DU qpectrophotometer used as a monochromator, calibrated .ucith the quiniiie sulfate spectrum of Kortum and Finckh.l This spectrum differed considerably from the quaiituni fluorescence spectrum given by Cherkasov, et a1.3 (we Table 11). It was therefore decided to redetermine the fluores(1) 0 Kortuin and B Finekh, Spectrochzm Acta 2, 177 (19$1-104 1) (-0) TT. H \Irliiiii.h N Z J Sca a n d Tcrh 37 2B. 1 1 (1055) ( 3 ) A S Clirrkaiov, B Pa QxesiiniAo\ and Cr 1 7'1.11rhinho Opttkn I S p p l t , 4 , 6'31 (1458)
763
ceiice spectra of quinine bisulfate and anthracene using a photoelectric met'hod similar to that described by R m d e t t and Jones,4 employing a phot'omultiplier in place of the photocell. Experimental
)
.
(2iiinine liiriilfttte T V ~ Sobtained from two sources; Car*EL Q ncgie Bros., Idondon, (B.P. grade) and BritishDrug Houses. Both lvere recrystallized from water and dried at 100'. The absorprion spectra of both samples in Ar H~SOI,mcasiirrtl with :LUnicam spectrophotomet,er, were found t'o coincide. Thc qiectruin agrerd closely with that puiilished l i j . C;r:trit anti Jones Anthracence was purified by chrom:itoyraphy on diiminz followed by siiblimat,ion in :I nitrogrii :i.t,niospherc. h IIilger :onstant tieriation spectrometer was set t i p ~ v i t h :L 931-A photomultip!ier a t the exit slit. The fluorescwt olutions \vc:re held in a disc-shaped cuvette kept at :I con25 O.l0) by means Of 'vat'er rirclllat'ed Fig, 1 FlliOreicrlrce spect,rllmof quinirlr \,iPlllfatc,5 x 1 0 - 3 it. Radiation from a mercury ]:imp .IT i n .Y H?SO,. s focussed on the front face of the ruvcxttc. i i c ~from the same fa,cr focursid t r r . Intensit,? measurements w r r tionietric method using a helipot r . amplifier as a nnlldetector. The linearity of the helipot (50,000 ohm, manufact,iired ti? 1'. X . Fos I,t,cl., England) was tested and found to Le hettrr than &0.3Yp from 200 to 990 divisions :md i l C ; 'rom 20 to 200 divisions. The 125 watt high pressii re merciiry lamp was regulated by placing harretters in series with it and running the unit from a constant voltage transformer. The wave length markings o n the sprrtrometer drum were checked nith t h e lint.5 from mercury and neon tlischargr Inmps. For the i4pectral energy calibrat,ion, a small coiled filament t,uiigstcn lamp ( 8 volt,s, 1 watt) %-as set in place of thr sample. The brightness temperature of the filament \\-:is ineasurrd with a calibrated o r h d pyrometer tnd the color temperature obtained' fiom ttrbles. The. coloi ttLmpernture T V ~ S2,200 =t50"Ii. I :inti the epr.ctr,tl energy distribution was a s u m r d to 23 21 22 23 24 25 2fi 2tie that of 1 hlack hody a t this temper:zture. For-3 -1 i o x v crn. , sythe and aZdams6 have shown that this procedure Fig. 2.-Anthracene-benzene, lO-jJI, 25 O , 1)roduces er -ors no greater than 1Yc in the n-ave length i:tngr 350 to 600 nip Thr transmission of the enven Limp \vas assumed to be constant over TABLEI 00 nip This procedure for calibrating OF SPECTRO-FLTTOROPHOTOMETER XITH A thc. monortirom:tt or-photo-multiplier combination allows CALIBRATIOX AT A COLOR TEMPERATURE O F 2200"I
