Yester Year No­bel Lau­re­ates - Pe­ter De­bye Veena Pat­ward­han - Spe­cial Cor­re­spon­dent

Phe­nom­e­nal Achieve­ments in Phys­i­cal Chem­istry

Chemical Industry Digest - - What’s In? - Veena Pat­ward­han, Spe­cial Cor­re­spon­dent

Pe­ter De­bye won a No­bel Prize in Chem­istry for his con­tri­bu­tions to the study of molec­u­lar struc­ture through his in­ves­ti­ga­tions on dipole mo­ments and on the dif­frac­tion of X-rays and elec­trons in gases. He had achieved such a tow­er­ing stature as a phys­i­cal chemist in­ter­na­tion­ally, that the Amer­i­can Chem­i­cal So­ci­ety de­cided to name its an­nual award for an out­stand­ing phys­i­cal chemist as the ‘Pe­ter De­bye Award in Phys­i­cal Chem­istry’.

When the Dutch physi­cist and phys­i­cal chemist Petrus De­bye first ar­rived from Europe at Cor­nell Univer­sity, Ithaca, New York, in 1939-1940 to de­liver the Baker lec­tures in Chem­istry, he was 55 years old, al­ready a No­bel Lau­re­ate, and ac­knowl­edged as one of the great­est sci­en­tists of the twentieth cen­tury. He had been awarded the No­bel Prize in Chem­istry for his con­tri­bu­tions to the study of molec­u­lar struc­ture through his in­ves­ti­ga­tions on dipole mo­ments and on the dif­frac­tion of X-rays and elec­trons in gases.

Af­ter com­ing to the US, he ac­cepted the po­si­tion of Pro­fes­sor of Chem­istry and Prin­ci­pal of the Chem­istry De­part­ment of Cor­nell Univer­sity in 1940 and took Amer­i­can cit­i­zen­ship in 1946. On re­tir­ing from this post in 1952, he was ap­pointed as Emer­i­tus Pro­fes­sor of Chem­istry at Cor­nell.

Pe­ter De­bye, as he now came to be called, had achieved such a tow­er­ing stature as a phys­i­cal chemist in­ter­na­tion­ally, that the Amer­i­can Chem­i­cal So­ci­ety de­cided to name its an­nual award for an out­stand­ing phys­i­cal chemist as the ‘Pe­ter De­bye Award in Phys­i­cal Chem­istry’. In a trib­ute to him af­ter he died, F. A. Long the Vice-Pres­i­dent and Pro­fes­sor of Chem­istry at Cor­nell Univer­sity said Pe­ter De­bye’s in­flu­ence on the Cor­nell Chem­istry De­part­ment and on Chem­istry in the US was pro­found. It wouldn’t be too far-fetched to ac­cept that his in­flu­ence on chem­istry in the world too has been im­mense.

Early ed­u­ca­tion and distin­guished aca­demic ca­reer in Europe

Petrus (Pe­ter) Jose­phus Wil­hel­mus De­bye was born at Maas­tricht in the

Nether­lands on March 24, 1884. He com­pleted his early ed­u­ca­tion at the ele­men­tary and se­condary schools in his home town, and in 1901, joined the Aachen Univer­sity of Tech­nol­ogy, fo­cus­ing on the study of math­e­mat­ics and clas­si­cal physics. In 1905, he com­pleted his de­gree in elec­tri­cal en­gi­neer­ing, and two years later, pub­lished his first pa­per – a sig­nif­i­cant math­e­mat­i­cal so­lu­tion to a prob­lem in­volv­ing eddy cur­rents. While at Aachen, he stud­ied un­der the cel­e­brated the­o­ret­i­cal physi­cist Arnold Som­mer­feld, who later openly re­ferred to Pe­ter De­bye as his most im­por­tant discovery.

In 1906, when Som­mer­feld re­ceived an ap­point­ment at Mu­nich, he took De­bye along with him as his as­sis­tant in the­o­ret­i­cal physics. In 1908, De­bye got his Ph.D. in Physics with a dis­ser­ta­tion on ra­di­a­tion pres­sure and there­after qual­i­fied as a Univer­sity lec­turer in 1910. That same year, he de­rived the Planck ra­di­a­tion for­mula com­ing up with a method that even Max Planck agreed was sim­pler than his own.

In 1911, De­bye took up the pro­fes­sor­ship at the Univer­sity of Zurich, Switzer­land that Al­bert Ein­stein va­cated on join­ing the Ger­man Charles-Ferdinand Univer­sity in Prague. Af­ter that, he changed uni­ver­si­ties ev­ery few years. He re­turned to the Nether­lands as Pro­fes­sor of The­o­ret­i­cal Physics at Utrecht Univer­sity in 1912, then moved to Göt­tin­gen, Ger­many in 1913 to lec­ture in ex­per­i­men­tal physics, there­after to the Swiss Fed­eral In­sti­tute of Tech­nol­ogy (ETH), Zurich in 1920 as the Prin­ci­pal of the In­sti­tute and Pro­fes­sor of Physics, and then to the Univer­sity of Leipzig, Ger­many in 1927 where he held a sim­i­lar po­si­tion. In 1934, he suc­ceeded Ein­stein as the Direc­tor of the Kaiser Wil­helm In­sti­tute for Physics (now called the Max Planck In­sti­tute) in Ber­lin and was also Pro­fes­sor of Physics at the Univer­sity of Ber­lin. From 1937 to 1939 he served as the Pres­i­dent of the Ger­man Phys­i­cal So­ci­ety (DPG). The po­si­tions he held from 1934 to 1939 were dur­ing the years that Adolf Hitler ruled Nazi Ger­many.

In­ter­est­ingly, de­spite his re­cur­rent ap­point­ments as a the­o­ret­i­cal physi­cist, De­bye had also spent sev­eral years lec­tur­ing on ex­per­i­men­tal physics at Göt­tin­gen. It is be­lieved that his close as­so­ci­a­tion with the ex­per­i­men­tal physi­cist Max Vien while study­ing at Aachen Univer­sity helped him ex­cel in ex­per­i­men­tal physics as well in later years. His last ap­point­ment was in the US at Cor­nell Univer­sity where he con­tin­ued en­gag­ing in re­search work till he died.

Re­mark­able sci­en­tist, bril­liant teacher

The ear­li­est of De­bye’s sev­eral ma­jor sci­en­tific con­tri­bu­tions was in 1912 when he de­vel­oped equa­tions to cal­cu­late the size of the molec­u­lar dipole mo­ments and also de­ter­mined in­for­ma­tion re­gard­ing the struc­ture of mol­e­cules. The mea­sure­ment of dipole mo­ments plays a sig­nif­i­cant role in un­der­stand­ing the na­ture of the chem­i­cal bonds be­tween the atoms in a mol­e­cule, distin­guish­ing be­tween po­lar and non-po­lar mol­e­cules, and de­ter­min­ing the shapes of mol­e­cules. De­bye’s work on the mea­sure­ment of molec­u­lar dipole mo­ments was so cru­cial that the units for these mea­sure­ments are named De­bye Units af­ter him.

In 1912, the same year in which he stud­ied the con­cept of dipole mo­ments, De­bye de­vel­oped the De­bye model for vibrations of atoms in solids ex­tend­ing Al­bert Ein­stein’s the­ory of spe­cific heat to lower tem­per­a­tures by in­clud­ing con­tri­bu­tions from low-fre­quency phonons. In 1913, he ex­tended Niels Bohr’s the­ory of atomic struc­ture by in­tro­duc­ing el­lip­ti­cal or­bits. In plasma physics and col­loid chem­istry, the De­bye length is de­fined as the dis­tance over which mo­bile charge car­ri­ers such as elec­trons screen out elec­tric fields. In 1923, to­gether with his as­sis­tant Erich Hückel, he de­vel­oped the De­bye-Hückel the­ory of elec­trolytic so­lu­tions, an im­prove­ment over Svante Ar­rhe­nius’ the­ory of elec­tri­cal con­duc­tiv­ity in elec­trolyte so­lu­tions. In 1923, Pe­ter De­bye also de­vel­oped a the­ory to ex­plain the Compton Ef­fect, named af­ter Amer­i­can physi­cist Arthur Compton, dis­cov­er­ing in­de­pen­dently that col­li­sion with elec­trons causes the wave­length of X-rays to in­crease. All of these con­tri­bu­tions bear­ing De­bye’s name are

sig­nif­i­cant ex­ten­sions of the mod­els pro­posed ear­lier by ma­jor sci­en­tists.

As a teacher, De­bye’s de­vo­tion to his stu­dents and sci­ence was un­mis­tak­able. He was al­ways cour­te­ous and friendly and al­ways happy to dis­cuss an in­ter­est­ing new idea with his stu­dents or vis­i­tors. He could as eas­ily ex­plain com­plex sci­en­tific ideas to school chil­dren as to his col­leagues. F. A. Long, who was a freshly ap­pointed as­sis­tant pro­fes­sor when Pe­ter De­bye first came to Cor­nell Univer­sity had also writ­ten this in his trib­ute: ‘Those (De­bye’s) lec­tures were lively, vig­or­ous, and filled with that sense of in­tel­lec­tual ex­cite­ment which I came to re­alise was a De­bye hall­mark.’ He said De­bye’s lec­tures were greeted with much en­thu­si­asm and that the Cor­nell fac­ulty were over­joyed when he ac­cepted the of­fer to stay on as Pro­fes­sor and Chair­man of the Chem­istry De­part­ment.

It is be­lieved that the pres­sure from Hitler’s govern­ment to give up his Dutch na­tion­al­ity had made De­bye de­cide to try to move to the US. A lot of his work at Cor­nell in­volved the use of light-scat­ter­ing tech­niques, fol­low­ing on his X-ray scat­ter­ing work done years ear­lier, for de­ter­min­ing the size and weight of poly­mer mol­e­cules. When World War II broke out syn­thetic rub­bers had been in­vented but it was es­sen­tial to know their molec­u­lar weight. This was made pos­si­ble by De­bye’s re­search dur­ing the war on small an­gle light scat­ter­ing. This re­search was later ex­tended to in­clude the study of proteins and macro­molecules.

Un­for­tu­nate controversy

A book in Dutch by the Dutch writer-sci­en­tist Sybe Ris­pens pub­lished in 2006 in­sin­u­ated that Pe­ter De­bye was a Nazi sym­pa­thiser who had re­moved sev­eral Jewish em­ploy­ees from the Kaiser Wil­helm So­ci­ety dur­ing his di­rec­tor­ship and as Pres­i­dent of DPG and even signed off his let­ters with ‘Heil Hitler’. How­ever, sev­eral in-depth in­ves­ti­ga­tions car­ried out sub­se­quently in the Nether­lands and the US re­vealed that De­bye was apo­lit­i­cal. The ear­li­est of these car­ried out by the Cor­nell Univer­sity’s de­part­ment of Chem­istry and Chem­i­cal Bi­ol­ogy is­sued a re­port in May 2006 that states:

Based on the in­for­ma­tion to-date, we have not found ev­i­dence sup­port­ing the ac­cu­sa­tions that De­bye was a Nazi sym­pa­thizer or col­lab­o­ra­tor or that he held anti-Semitic views. It is im­por­tant that this be stated clearly since these are the most se­ri­ous al­le­ga­tions.

Even decades be­fore Ris­pens, sev­eral writ­ers had clearly men­tioned De­bye’s staunch re­sis­tance to Nazi ac­tiv­i­ties. Many sci­en­tists and schol­ars have pointed out that the DPG had suc­ceeded in re­tain­ing their threat­ened Jewish staff as long as pos­si­ble de­spite in­creas­ing pres­sure from the Nazis, and that as a civil ser­vant, even Max von Laue, a lead­ing op­po­nent of the Nazis was obliged to sign let­ters with ‘Heil Hitler’. Be­sides, the help De­bye and his col­leagues ex­tended at great risk to them­selves and their fam­i­lies to their Jewish col­league Lise Meit­ner to cross the Dutch-Ger­man bor­der and go to Swe­den to es­cape Nazi per­se­cu­tion is well doc­u­mented.

Oth­ers point out that when De­bye re­ceived the Max Planck medal of the DPG in 1950, no­body, not even Ein­stein, Max von Laue, and other Jewish sci­en­tists who knew De­bye closely, ob­jected.

Awards and recog­ni­tions galore

The hon­ours be­stowed on this out­stand­ing sci­en­tist are too many to list here, run­ning into scores, some of the prom­i­nent ones be­ing the No­bel Prize in 1936, the Rum­ford Medal of the Royal So­ci­ety, Lon­don in 1930, the Lorentz Medal of the Royal Nether­lands Academy in 1935, Lon­don, the Max Planck Medal in 1950 by the West Ger­many Phys­i­cal So­ci­ety, and the Pri­est­ley Medal of the Amer­i­can Chem­i­cal So­ci­ety in 1963.

De­bye was a Vis­it­ing Lec­turer at uni­ver­si­ties across the US and Europe and as­so­ci­ated with nu­mer­ous sci­en­tific academies across the world in­clud­ing the In­dian Academy, Ben­galuru, and the Na­tional In­sti­tute of Sci­ence in In­dia.

We owe a num­ber of the con­cepts in chem­istry that we of­ten take for granted to­day to De­bye who proved these af­ter metic­u­lous ex­per­i­men­tal mea­sure­ments. His pas­sion for sci­en­tific work never flagged till the end. He died of a heart at­tack on 2 No­vem­ber, 1966 at the age of 82 and is buried in the Pleas­ant Grove Ceme­tery at Ithaca, New York.

Ref­er­ences

1. No­bel­prize.org: Pe­ter De­bye – Bi­o­graph­i­cal – No­bel Me­dia AB 2014 – https://www.no­bel­prize.org/no­bel_prizes/chem­istry/lau­re­ates/1936/de­bye-bio.html

2. Elan­gan­nan Arunan: Pe­ter De­bye – Res­o­nance, De­cem­ber 2010, In­dian Academy of Sci­ences.

3. Fa­mousS­ci­en­tists.org: Pe­ter De­bye – https://www.fa­mouss­ci­en­tists.org/pe­ter-de­bye/

4. F. A. Long: Pe­ter De­bye – An Ap­pre­ci­a­tion – Sci­ence, 24 Feb, 1967: 979-980.

5. Euro­pean Syn­chrotron Ra­di­a­tion Fa­cil­ity: His­tor­i­cal Notes on Pe­ter De­bye.

6. http://www.esrf.eu/User­sAndS­cience/Ex­per­i­ments/CRG/ BM26/SaxsWaxs/De­bye.

7. ChemViews: 50th An­niver­sary: Death of Pe­ter De­bye – ChemViews Magazine, 02 No­vem­ber, 2016.

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