Vol. XVII. 4 REVISTA MEXICANA DE FISICA

DOSIMETRY STUDIES AND RADIOLYSIS OF

AQUEOUS SOLUTIONS OF CHLORAL HYDRATE

J. Reyes L.", S.A. Reyes L.

Instituto de Física, Universidad Nocional de México

M.A. limón M.

*Programa de Aplicaciones Industriales de la Radiación

Comisión Nacional de Energía Nuclear

(Recibido: 30 Octubre 1968)

AHSTRACT

1968

Th(' radica/s ;,moltJ('d in /hl' radiolysis 01 0.2M aqut'ous solulicms 01Chlr.ral hydralt' are idC'rJ/ilit'd by mt'l1TIS 01 thl' t'/t'clron paramagndic resonarJct'

arld mass s/Jí'c/rome/ry data 01 irradia/('d polycrys/allinc powdt'r and sirJg/t'

crys ta Is 01 Ch lora I hydra/t'.Dosiml'lry s/udi('s fl't'rfO also dOTll' wilh aqut'Ol15 solulirms 01 ehloral

hydratl' at sl'lJoal molar COTlCOltraliorlS. Tht' llariation 01 pll ul thl' irradialed

solutlOns with dost' may bl' uSl'd as a dosim("/ric rl'lation ill thfO 10/0700 rads

dosl' intt'rva/ with good aCCllraC)'.

263

RI!S[I,III!S

Los radica/es iu/ermf'diario,"i d€' lo,"i r('o('(';01/(.",", ;'lducidas por la radiación

ianiz(Jnte ('11 S o/uc imu."s oc uosas 0.2,\1 de r./ora I hidratado s (Al idf?ntijicadus a par.

tir de los datos Ohll"'lidos d(' la T(,sOI/Qneia paramagllética declrólI;ca )' tiC' f'5~C-

troml' Iria d(' mas as de polr'o polier is la li!lO )' m(mocr is la 1('s dI" e lora 1 bidra tad o irra-

diados.

También /Uf'T'l'l realizados ("studios dosimétricos C011 suluci(J1J('s acuosas

de Claral hidratado a dil'(,Tsas C01/u'lllracirH]€,s mola,('s. La variació,¡ del pll d!'

las soiuciorl(,s i"adiada$ con la d05;s pUf"de S(,T ('mp/t"oda Cf)mo Ima re/ación do.

simétrica 01 ('/ ;n/f'rt.,% dí" 10 a 700 rads ('mi hUl'llQ pr('ci-;ió'l.

RADIOL YSIS OF AQUEOUS SOLUTIONS OF CHLORAL HYDRATE.

The Rodiotion Chemistry of aqueous solutions of Chloral hydrate has been

studied in the p::Ist by Andrews 1, Sugimoto2 ond Spinks, et oP' 4. s. Mclntosh5

proposed the foJlowing mechonism!or the radiolysis:

IH, O VVV\IVv----+ R (1 )

R + S

S t O,

H,O

S t R

SO2

3 oc id + R

) stable product(or product5)

(2)

(3)

(4 )

(5)

,.here I is the dose rote, R is very I¡ke Iy • H or • OH, or even both, S represents

'1 molecule of Chlerol hydrote, o dot over o symboJ representing o free rodicol,and

"ocid- corresponds to Hel.

The Primory interoction of the radiotion with water in dilute oqueous so-

2M

lutions as postulated in (1) is generally accepted. The reoctions (2), (3) and (4)

Jormachain mechanismwhich is consistentwith the lorge G(HCI) values ob.

served by several outhors (references 1 to 5) ond with our observotions (> of the

cons ideroble voriation in pH of the irradiated solutions between 10 rods .Q 1.5

Mrads.

Sorne deductions about the radical S moy be done from a considerotion of

the overall octivation energy fer the production of acid. According to Mclntoshs ,

it moy be speculated, -since the overol! octivation energy for the Chlerol hydrate

radiolysis is less, or ot the most, equal to that for Bromol hyclrate3• 4. 7_, that

the free radical S has resulted from On ottack on the aldehyde end of the Chlerol

hydrote molecule by R. If the ottock wos on the hologen end of the molecule, the

activation energy for the production of acid would be higher for Chleral hydrate

solution because the C-el bond strength is greater than thot fer the C-Br bond.

Radico I S has not been identified and that is the purpose of this part of the papero

Polycrystalline powder ofChlorol hydrote (Baker, 1568) was irradiated .•.•.ith

1.0 MeY electrons, in air, ot room temperature, in o 1 mm thickness loyer, usingthe

Electron Yan de Groaff Accelerotor at the Instituto de Fisica, UNAM. Dose rate

was determined with the relotion:

(n. R.) , (6)

where (!J. R.)s and (V. R')d are the dase rate for the c:.nmple and dosimeter re.

s pect;ve Iy. We used os dos imeter the powder of Cobo lt~ctivoted boros i licate

glass (CABS), for which o dose-ESR signal intensity relotion has been obtoined

by o method described before8• The mass stopping powers fraction mSs/mSd has

a value of 0.99, calculated from the formol definitionQ, according to the doto of

Henricksen10 ond using the following volues of the oppropriote constonts:

,65

CABS Ch IOfa I hyd,ate

Mean dens ity (91 ce) 2.266 1.908

Effective atomic number 9.337 8.2

tJeon number of otoms

pe' ce (X 10") 0.737 0.696

Mean ionizotion paten'ial (eV) 126.9 111.5

Electron irradiotion induces poramagnetic species in polycrystolline

Chlcral hydrote, corocterized by the ESR spectrum shown in figure l. The ESR

determinotion was mode ot room temperoture using the Varion 4502-15 EPR spec.

trameter ot the Instituto de Físico, UNAM, operoting ot o microwove frequency in

,he X-bond neo, 9.4 GHz wi,h 100 KHz ¡ield modulatian.

The concentration of poromognetic species vories wíth dase occording to

the relation plotted in figure 2. Three kinds of behovior ore in evidence: firstly,

the formation of poromagnetic species in tne ronge up to 40 Krods; secondly, the

sublimation of fhe irrodioted somples ond reactions between active species in-

duced by irradiation to form HCI ond other products os wos reported by Plotford4,

ond finolly, o saturotion in which equilibrium sets in between the reactions ond

the formotion of paromognetic species.

Becouse the time decoy of the induced IXIromognetic species at room

temperature is s low, as shO'Nn in figure 3, there is negligible loss of the number

of IXIramagnetic species during the time necessary ta prelXlre a salution. Hence

it is pass ible ta compare the .'oriatian in pH w ith dase af the salutian prepared

with the irrodioted powder with that for the irradioted Chlarol hydratc solution.

Aqueaus solutions were prepored with distilled (pH = 5.85) ond tridistilled

woter (pH = 6.12), which wos then further purified by distilling first from On alko.

line permongonote solutian ond then from On acidic dichromote soJutian.

The solutions were irrodioted with 1.0 t},eV electrans, ot room temperature,

placing 7cc in Petri dishes on o rotating arroyos described by Ademll• The

2M

sample thickness was abaut 3mm. Dosé rate was calculated using relatlon (6).". ' .• (/). R~)d was determined by means of the Fricke me thod 12 , using13

G(Fe'.) = 15.45 t 0.11.The pH variatian of the solutions prepored with the irrodiated powder was ~

found to behave in the same way as that of the irradiated solutions.as can be seen

in figure 4. These gaphs cannot be compered directly beca use far the solutions

~epored with irradiated paNder, the radiation absorbed energy forms only the poro-

mognetic species that reoct with water when the solution is prepored. The con-

siderable pH variatian is explained if the poramagnetic species react through the

cha in mechanism of reactions (2) to (4).

Oue to the difficulty of obtoining further information from the irradiated

polycrystalline ESR spectra, it was necessary to prepore a single crystols of

ehloral hydrate.Smoll Chleral hydrate -leofs" about 3 to 5mm lorge were obtained byevapo-

ration over copper from molten Chlerol hydrote at 48 i. O.l°C after 48 to 72 hours.

Chlorol hydrate could also be recrystallized from a Chloroform solution, but upon

repeated recrystallization hexagonal tabular crystals come to graN slawly. After

48 to 72 hours the single crystals grow to sizes of 2 to 3mm in diameter.

The irradioted single crystals maintained in normal ESR sample holders

we!'e placed in o cavity (Varian 4533) that could be rotated so as to enable the

variatian of the magnetic field direction with respect to the crystol planes. In

this woy it was possible to get more resolution on the spectra lines.

ESR spectra is composed of several lines, as is shown in figure S, where

severo I spectro were necessary to draw to identify the poramognetic species.

The initiol distribution observed for low magnetic Held values in spectra 1,2 and

4establishes an intensity sequence of 1:4:8:12:15:16:16:15:12:8:4:1 thatwas

assumed to correspond to the CCI e (OH) radical, where the unpoired eleetron, 2

interocts with 3 equivalent Chlorine atomS ond 2 equivalent protons. A second

sequence is o Iso observed, 1: 5: 12: 20: 26: 26: 20: 12: 5: 1, that was ossurred to cene-

spond to the éCI CH (OH) radical, with the unpoired electron interocting with o2 2

¡:::rotan, 2 equivalent Chlorine otoms ond 2 equivalent protons, hydroxyls. Unfortu-

note Iy it was only pass ible to eva lucte the initio] iotens ity sequence in both cases,

267

due moinly to poor uniform resolution of spectro through the mognetic field

sconning. Hcmever, our ESR informotion is enough to estoblish the existence of

these two radica Is.

Mass spectrograms (MS) were also obtained for irradiated and non-irrodi-

oted samples, using the Hitochi Perkin-Elmer RMU-6D Mass S¡:>ectrometer at the

Instituto de Química, UNAM. Table 1 presents the relotive abundonces of the

moin ion found for irradiated ond non-irrodioted somples with respect to moss 82.

From the [H O] + ion relotive abundance in both samples it is determined2

thot irrodiotion induces deshydration of Chlerol hydrote.

The production of HCI observed by Platford4 in the irradiation of salid

Chlorol hydrate moy be exploined by reaction (7) (see collection of reoctions

Toble 11). By this mechonism the formation of the CCI3

é(OH)2 radical by irradi-

ation may explain the interaction of the unpoired electron with 3 equivolent

Chlorine atoms and 2 equivalent protons observed in the ESR spectra. Upon so-

lution this radical reocts with water (reaction 8) giving onather radical, CCI2-

COOH and HCI. This second radical reacts with water (reactian 9) to give CHCI-2

COOH or CCI C (OH) and. OH, whieh moy reael with Ihe Chleral hydrale mole-2 2

cule to give ogoin the (C12 COOH radical and HCI (reaction 10) ond storted the

proposed chain mechanism. The product CHCI COOH contributes to the ocidity2

of the solution that chonges its pH va lue as is observed in figure 4.

The radical CCI CH (OH) may be formed with the irradiation through2 2

(reaction 11) giving place toChlorine otoms. The relative abundance of Chlorine

ions observed in the MS of non-irrodiated and irrodioted somples (Toble 1) is ex-

oloined by mecns of this mechanism. The obundance for the irrodiated sample is

Icmer thon in the case of the non-irrodiated somple. In solution, the éCI CH (OH)• 2 2

radical reocts (12) with water to form the CCI COOH radical HCI rl one! • OH2 " 2

which reoct os was explained in reoctions (7) to (lO). It is 0150 interesting to

n,-.~ that the CCI2 COOH radical is deshydroted (13) in the moss spectrometer. .¡.;~~-heater to give the CCI CHO radical thot when it is ionized gives the C Cl CHO

2 2

ion with relotive obundance greater in the irrauioted sample thon in the non-irradi-oted, as is expected.

268

In solution, under -OH octivity, reoction (lO) takes place, os was obtained

by Dixon15• He bosed his interpretation en the ESR spectra of the CCI? COOH

radical in solution.

However, .he radical. CCI C (OH) ond CCI CH (OH) exploin .he ESR3 2 2 2

doto, and reactiens (7) to (12) explain the mechonism of the radiolysis of aqueous

solutions of Chloral hydrate throuQh the CC1.., COOH radical.

DOSIMETRY STUDIES

In irradiation of biologicol systems one of the main considerations is the

determination of absorbed dose with adequate ~ecission.

F or X or gamma radiation, the determinotion of absorbed dose can be done

using the expression

(14)

where lJ.~ and Dd ore the doses, (p./p)_~ and (P./P)d the mean mOSs energy ab .•

sorption coefficients for the system and dasimeter respectively.

lJd can be determined us ing a secondary dos imeter, with phys ica 1ond

geometrical charocteristics similar to the system. The values of the coefficients

can be calculated from dato of the radiation source, system ond dosímeter.

[n particular, when bOCo gamma radiation is used, with mean energy of

1.25 MeV, relaHon (14) con be replaced by

/1 =, (z!A),____ . /Id

(Z!A)d(15)

where (Z/A)s and (Z/A)d ore the mean electron densities of the system and

aosilT'eter respectively.

269

For heterogeneous materials, the value of (Z/A) can be calculated from

(Z/A) = ::£w. (Z/A).¡ I •

where w¡ is the weigth fraction and (Z/ A)¡ the electron density of the ith element

in the medium.

In the case of X.rays with a known energy spectrum the radiotion beam can

be considered os the sum of mono--energetic beams that are absorbed independently

by the material. The mean coefficient is a function of the energies and of the

number of photons in each energy ronge. 1f the spectrum ond the voriation of the

coefficient with energy are known, both can be combined graphica lIy to obtoin the

mean coefficient for each of the materials, beca use

(I'/p)

where (f-L/pl¡ is the mass cQPHicient for the ith element in the medium.

Several primary and secondary dosimeters have been used to determine the

volue of Vd for biological systems, but in the cose of low level radiotion sources

it is still necessory to developo secondary dosimeter with charocteristics similar

to biological systems, especiolly in the case of X..,ays irradiations.

It has been founded by Boyd1fi and Sugimot02 that aqueous solutions of

Chloral hydrote can be used as o secondary dosimeter for low level doses.

The plXposes of this part of the pa¡:;er ore: firstly, to study the effect of

60(:0 gamma radiotion, up to ~.O MeV X..,ays ond 1.0 MeV electrons on oqueous

solutions of Chloral hydrote at severo I concentrotions. Secondly, to find sorne

relations between the pH variation and dose in severo I dose intervols.

The 1.0 MeY e lectron irradiations were performed os was described before.

Bremsstrahlung X..,ays were obtoined from the gold target arrayl7 of the Accelerota

and the solutions exposed in o 5cc Kimax tubes with bakelite screwtops in the

form described in detail by Limón6•

270

A 3500 Ci 01 "'Co Gommocell 200 (Atomic Energy 01 Canoda Ud.) ollhe

• Laboratorio Nuclear, UNAM, wcs used far gamma irradiations, using the sorne

container os in X'1'oys experiments placed ot o s pecio I support as wos described

by Ademll •

pH determinations were dt>ne with two potentiometers, a Photovolt (model

111) ond a Beckmon (mode I expondomolic) w ilh a p-eciss ion 01 t 0.05 ond 0.01 pi;

units res pective Iy.

l. t: I~ctrons

Figure 6 shO'W"s the relotion between the pH of the solutions and dose, in

which it is possible to opp-eciate a constant change of the pH in the dase ronge

sludied. This change is due moinly to the p-oduclion 01 HCI lamed rodiolytieally.

The variatian of the pH with the concentratían is shown in figure 7. These

data COn be exploined ñom the experimentol results of Plotford", who performed

experiments with 9OSr_90y beta rodiatían ond observed that the G (Hel) volue

¡"creases considerably with the molar concentrotion of the solutions. These re-

.sults were plotted in figure 7 for comporation with ours.

2. X.,ays

Dosimetry wos made using the relationl(14) and considering

G(Fe3+) = 14.97. This value was obtoined from a graphic combination of the

variation of G (Fe3+) with energy and olso by making use of the X-ray spectrum

in the 0-1.0 MeV range. The volue of (I'/p),/(I'/P)d for different concentrolions

ore shown in Toble IlI. The X-ray energy spectrum was obtained from experi •.

mental doto after Edelsack18 and plotted in figure 8.

Fiaure 9 shows that the pH of the irradiated solutions at different concen"

trotions obout 0.2 M varíes linearly with ahsorbed dose in the 100 to 700 rads dose

ronge.

271

3. Gemma rediction

Dosimetry wos determined with relotion (15) using the Fricke methOO12 to

meosure Ddond colculoting the values of the froction (Z/A) ..••/(Z/A)d fordifferent

concentrotions. (Toble 111).

The result of the irrodiotion can be ohserved in figure 6, where the re-

sponse of the solution for high" doses is le~s thon in the cose of electron irrodi.

otions, due ta the difference in dose rote, 9.28 Krod/ min for gammas ond from

00159 ta 1.44 Mrod/min for electronso

Aqueous salutions af Chlorol hydrote con he used far low level dosimetry

ot different concentrotions, with goOO occurocy due ta the preciss ion in the pH

meosurements ond olso becouse there is no difficulty in the salutian preporotions.

It is found thot the expression

IJ =(PI/)o - (pl/)i

4.45x 10' (red.) (18)

can be used os o dosimetric relotian for cancentrotians between 002 tlnd 1.0 M,

where (pll)o ond (p/I),ore the pH af the original ond irrodioted solution respective-

Iyo For (pIl)o volue outside this ronge, the dose con be reod directly fram the

groph by drowing o curve porollel ta the neorest colibrotian curve, storting from

the pH volue of the original solutian. By this method the indeterminotion of the

meosure of the dose is 5% between 200 ond 600 rods ond obout 10% out of this

ronge. The doshed lines in figure 9 moy be helpful in drowing these ouxiliorly

lines. In the SOrne figure it ,;on be observed for concentrotions less thon 0.05 M

the voriotion of the pH of the irrodioted solution decreoses ropidly for doses less

thcn 100 rods. In arder to better estoblish this voriotian, severol 0.05, 0.005 ond

0.001 M concentrotions were irrodioted with X"foys, determining the pH voriotian

in situ. The pH meter electrodes were ploced in the somple container ond reoding

ta"ing directly by use af o Honeywell Electronic 15 recorder (0- 2.2 mV ronge).

The results are shown in figure 1Owh~re the voltage voriotion has been converted

to pH varjotion. rhe peaks ot low doses, less than 15 rads, ore due to the un-

272

stability of the electrodes current when the radiation beom is 011. The recorded

data.fer 0.005 M solution may be used as a dosimetric -relation between 10 to 100

rads with a precission about 1 to 2%. This result is particularly useful for Radi:-

ation Biology research. Graphs fer 0.05 and 0.001 M solutions can be also used

fer dosimetry wíth an indetermination about 5% due to the fact that the pH vari.

ation is less than in the case of 0.005 M solution. In conclusion, the dosimetric

relations found in this poper are useful fer determining the amount of radiation

energyabserbed in biological systems when subject to X, gamma and electron

irradiations.

ACKNOWLEDGMENTS

We wish to acknowledge the assistance of Fís. Alejandra J. de De Alba

fer her comments to the initial dosimetric studies, to the personnel of Laboratorio

Nuclear for their help in performing the gamma experiments, to Dr. :-iécta- t-lenchaca

fa- his he'lpful comments to establish the chemical reactions mechanism, to Mr.

Eduardo Cortez, who performed the MS determinations at the Instituto de Química,

to Fís. Héctor Riveros for his helping to obtoininQ the single crystals and finalJy to

Mr. Francisco Velózquez fer his constant help in the operation of the Accelerator.

REFERENCES

l. H. L. Andrews and P. A. Share, J. Chem. Phys. 18, 1165 (1959).

2. K. Sugimoto, et al, Bull.Univ.Osako Pref.Ser. A, 11,67 (1962).

3. G. R. Freeman, A. B. Van C leove and J.W. T. Spinks, Con. J. Chem. 31, 1164

(1953); ibid, 32, 322 (1954).

4. R.F. Platlard and J.W. 1. Spinks, Can.J.Chem. 37,1022 (1959).

5. R. G. MeIntas h, R. L. Eager and J. W.1.Spinks, Can. J. Chem. 42, 2033 (1964);

ibid, 43, 3490 (1965).6. M.A. Limón M., Tes is Profesional, Facultad de Ciencias, UNAM (in prepa.

ratlon).

7. R.J.Waoos and J.W.T.Spinks, Can.J.Chem.35, 14/5 (1967).

273

8. S.A. Reyes L., E. Muñoz P. ond J. Reyes L., Rev.Mex.Fís. 1~, 31, (1967).

9. A.T. Nelms, US Na!ional Bureau 01 Standards, Circular 577 (1956).

10. T. Henricksen and J. Baarli, Radial.Res. 6, 415 (1957).

11. E. Adem C., Tesis Profesional, Facultad de Ciencias, UNAM (1968).

12. H.A. Battaerd and G.W. Tregaer, Rev.Pure Appl.Chem.l<, 83 (1966).

\3. R.H.Schulerand A.O.Allen, J.Chem.Phys. 24, 56 (1956).

14. K. Ogawa, Bull.Chem.S~. Jopan 36, 610 (1963).

15. W. T. Dixan, el al, J.Chem.Soc. 3625 (1964).

16. W. Boyd, el al, US AEC TID-21634 (1965).17. The torget wos des igned and constructed by High Voltoge Engineering

Corporation, Burlington, Moss. USA.

18. E.A. Edelsack, el al, Heallh Phys. 4,1 (1960).

274

WASS lOO NOlI-IRRADlAT[O IRRAOlATEO~.~ 1%1 1%1

" ,.. 0.7

.9 CN_O" "1 ,~.•• ,,+

11.6 6.937 ,,+ ~. ..1

'7 "C..-o H • [C~J'OH >0.0 ~.,•• [H 212 14.'

•• [~:J • ~+J 24.1 17.1

>O ~'-~ •.9 • .1. , t+~ '.9 •••

•• ~I-C-C~+ 100.0 1000

e¡8 , + e-N 33.9, 36.1e,8 • @l-C-C~+ 65.6 68.9

8 •í'

+ e-H 21.1 22 .•).

8. [a-c-~+ /2.4 I~8

e¡8 7 te-H 32 '.0,e,

e,' e,'"' CI-e-e"-o N-e-c. o. ~., 39.7+ .'.'/3 '6om 19.7 25.5

,1> - '.9 ..,e,' +,.. CI-;.-CH.O ..9 '.8

,.8 - '.9 '.8

150 ,•... 1.0 ,.8

"2 - O., O.

Toble l. Relotive abundance of the ions deteeted with mOSS spectrometry fornon.irrodiated ond irradiated samples of Chlorol hydrate, using theHitochi Perkin~Elmer RMU-tD Moss spectrometer. Relative aburdanceis shown with respect to mOSS 82.

275

el H •.••.•I I/vn

CI- c- eI '()lCI

'r!A''''''"• CI el OH, /

cae + HelCI/ 'oH

171

Ci "'0CI- e-e + Hel

'OH

el H o'e-e' +'OH

el,/ 'OH

181

191

+ H,o

CI H/'H el OH el o1 I 1 "/ 'CI-C-C + .OH---- •• CI-C-C -cr-c-c + Hel¿ ~ ¿ ~ . ~ (la)

,0

el H OH

CI-t-t/di "OH

el H OH___ ~-V +'CI_

CI/ 'OH

CII

CI-C-C'OH

(111

U21

CI H/OH'\. I

/"'-C"CI OH

IoI-H,OI(13)

Toble 11. Collection of reactions of the irradiated Chloral hydrate powder ond therodicals formed radiolytically.

276

Molar concentration (I'/p). (Z/ A).(M)

(I'/P)d (Z/A)d

1.0 0.8731 0.9869

0.9 0.8832 0.9887

0.8 0.8918 0.9905

0.7 0.9011 0.9920

0.6 0.9105 0.9940

0.5 0.9198 0.9960

0.4 0.9284 0.9960

0.3 0.9385 0.9989

0.2 0.9470 1.0000

0.1 0.9501 1.0000

0.05 0.9579 1.0000

0.01 0.9642 1.0000

0.005 0.9649 1.0000

Table 111. Colculoted values for the meOn mass energy absorptioncoefficients ond e lectron dens ities re lations for severa Imolar concentrations.

277

•

•

3361.5G

oG'>

f

3492.5G

Fig.1. Typicol ESR spectro of electron irradiated polycrystolline Chloral hydrotein air ot room temperature to dO Krads. Values of the field ore shQ'l/rin ingauss (G).

278

o.,.,

I ! II Q I

o•....

2

oID

oCD

ov

o2

oen

oN

o.,.,

o.,.,

w(f)

8

"OIUo"~.•ID.,.,.,.,"o::ci

Fig.2. Production curve of poromagnetic 5pecies ot differenf doses in electronirradiated polycrystolline Chloral hydrate in air ot room temperature.h/w represents ~he peak fa peak height of the first derivotive of the reso.nonce signa! per moss unit. O.R. represents the dose ratee

279

oO

"o=-~~;;w N - N~ N -

OO O •

oO

o -~.<

o -~

o~

o!

o~

o~

~

o~

o~

o~

o~

o•oo

o•o~

oN

~

OO OO

Fig.3. Concentrotion of paromognetic species remOlnlng versus time of storogeot room temperoture. h/w represents the peak to peak height of the firstderivative of resononce signal per mass unit.

280

. .-

Irrodiofed polycryslolline Chlorol hydrole 0.2 Moqueous solufion

Irrodioled 0.2 M Chlorol hydrole solufion

-n

'"'"

'" o "_~Io <-;::.ir 11'I ~.• •_. - -+~ ~ o'&- Q' ~_. ~ oo -- "~ ' -o. ~ Tp~:"'~O;:o..e\11 ~ ~.o :;: g

....., c:T1II

~ ~.~.~o e _.?a.:rQ' a..¡; o0."•n'""-nQ ea ';~

-< :Poo., ne. Q~ "•" "~~0.'• o.;' "nOe -" ""< ~•

pH

4.~ 1-

4.0

3.5 1- -

30

2.5 1-

2.Cb:oolI

pH

40 ~

H1 •.

3.0

2.51-

2.0

I.~1-

0.01

0.002

0.02

-.

0.03

0.005

0.05

0.01

...L0.1

0.02

0.2

A

0.03 0.04 0.05Dose (ll rod.)

B

•

0.3 0.4 0.5Dose (llrod. J

0.1

1.0

5150 -

~~f>0-

3370 -

~380-

3390 -

~400-

)410 -

34Z0 -

3430 -

~440 -

3450 -

~4f>0-

3470 -

3480 -

3490 -

3500 -

3510 -

35Z0 -

35~0 -

~540 -

3550 -

~5f>0-

3570-

oO.

NO• %

;: ~ ¡¡%

iN-

1~• i l~

ª3384

;¡;

"' •..• "' ... ~403

ji;:;;;:;;", 3414

•~. "~o ".•N- ".N

N_

"O'

;;;¡; 3489NO~."'"•

~ 35Z7

1

N

Fig.5. ESRroting ot o microwove frequencyin ththe initiol experimenta! relotive

inteto Is.

282

o

p ,,I

'" '" '" '" '" :1 ~~o o ~o I ~o N ~ O O I :lIO O O 1- ~

I

:/O

O • - O • ~ '"~ d V>e i I O

g " '"u • • I

'" I ~W a: <{ O

> ,., ,

:/•:1 o IU

O o , N

• I Oo ••I

:1I,,I

~

I,,0,0,0, t:1.- ~I O, O• •,, O, Or, ~, O, O

•

;1NOO

, f10~tO

O ~ o ~ o ~ O ~ o ~ O ~'" ".; ".; " ••• ,..¡ ~ N N O

:t:Q.

F ig. 6. pH variation of the 6OCogamma ond electron irrodioted solutions. Thisvoriation is due moinly to the production of Hel formed radiolyt:colly.

283

~ o o o o o oo o o o o ou '" '" '" .... N

Z '--I-¡Q, I ~'" ,

~ ~~ ~

\\\\\\\

\\\

\\\\\,~,\11I,1II,II1II1IIIIIIIII

~O

'"~~

'" m.uO ~oU

'"OO

oO

"Fig.7. pH variotion of the electron irradioted solution at severol doses. Thevoriotion of G (Hel) found by Platford4 exploins our result ond it isplotted for comporotion.

284

JO"

10"

1O"

, A. A. A, A, A, A, A, A, A" A" A" A" A" A"I O'

1.3 1.4 ~.~0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.8 0.9 1.0 1.1 1.20.02E ("'eV) 1.415

Fig.8. Bremsstrahlung spectro fqc 1.Qond 1.5 MeVeleetrons on a gold target,ofter Edelsack. (1) represents the intensity of the X""oy beom inphotons/sec f1A sterodion and wcs measured as was described byEde Isock 18.

285

pH

55

o 0,05 MJ:J O.JO M• 0.20 Jo!6. 0.75 MX 1.00 M

Molar Concentration

- -100 200 lOO 400 500 600 700 BOa 900 1000

DOSE ¡,,'I

Fig.9. pH variation of the X""oy irradiated solutions. This relation can be usedas o dosimetric relotion.

286

5.60

pH

5.50 \i\\\

pH

5.50

0.004115.40

5.30

5.20

5.10

\ ,,"o

Beaman

" ,

"," ,,,,," ,,,,,

"- ,,,"- ,

"- ,,,," 0.005 M,,,,,,,,

5.00

4.50

4.40

4.30

70 BO 90 100Dase (rad)

Fig.l0. Dose converted recorded pH variotionwith X-rey írrodiotion of Chlorolhydrote solutions. Molar concentrat;ons are shown in the figure. Thepeoks at low doses ore due to the unstobility of the eleetrodes Current

when the rodiotion beam is on.

287