RESEARCH in Brief

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RESEARCH in Brief

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CHEMISTRY

Diamonds – Assembled from Nitrogen

enormously high energy densi-ty. This is explained by the factthat there is much more energyin three single bonds betweennitrogen atoms than in onetriple bond. It follows that a lotof energy is released when sin-gle-bond polymeric nitrogentransforms into normal, triple-bond nitrogen – in fact, asmentioned above, more thanfive times as much as is re-leased by the most powerfulknown chemical explosives.As the final product of this ex-plosive conversion is ordinary,environmentally friendly nitro-gen, it is now being examinedwhether and how polymeric ni-trogen can be used as a fuel orexplosive. To achieve this, how-ever, it is first necessary to finda way to obtain “diamond” ni-trogen at normal temperaturesand pressures. ●

Further information from: DR. MIKAIL EREMETS, Max Planck Institute for Chemistry, Mainz

Tel.: +49-6131 305-312, Fax: +49-6131 305-388e-mail: eremets@mpch-mainz.mpg.de

DR. REINHARD BOEHLER

Max Planck Institute for Chemistry, MainzTel.: +49-6131 305-252, Fax: +49-6131 305-388e-mail: boe@mpch-mainz.mpg.de

Polymeric cubiclattice structure:All nitrogenatoms are linkedto each otherthrough singlecovalent bonds.

Since 1999, the EuropeanCentral Bank has been set-ting interest rates for all euro zone member states. As a result, the individualcountries find themselvesfacing a dual challenge: onthe one hand, they have tomanage their economic poli-cies without a monetary policy of their own, while onthe other they are strugglingto compensate for entirelynew destabilizing effects ontheir economies. In his study,Henrik Enderlein of the Max Planck Institute for theStudy of Societies concludesthat within the opportuni-ties available to them, thesecountries have adapted wellto the new situation. But the problems have not yet all been solved. Germany, inparticular, has found itself in difficulties with high realinterest rates and a decen-tralized system of public finances. A common Euro-pean economic policy mightoffer a way out, but standslittle chance of being im-plemented.

The European Central Bank setsinterest rates for the membersof the European MonetaryUnion on the principle of “onesize fits all.” Its decisions arebased on economic averagesfor the euro zone. And the re-sults are less than tailor-madefor individual member states:for some, real interest rates aretoo high – for others, too low.Since the EMU began, Germanyhas had to deal with real inter-est rates that are far too high.The differing real rates have the effect of either slowing oraccelerating the economy in in-dividual countries. Since, how-ever, the member states havehanded over monetary policy toa European level of direction,their only means of control isvia fiscal and wage policy.

But how should such instru-ments be used to stabilize eco-nomic cycles? It is this questionthat lies at the hub of the cur-rent debate over a renaissanceof demand management poli-cies. Since the mid-1980s, fiscaland wage policies have beenmore or less superfluous in sta-bilizing the economy, giventhat this task had almost en-tirely become the province ofthe central banks and therebyof monetary policy. However,monetary union brought freshchallenges for the cyclicaleconomies of the euro zonemember states. How did theyrespond? Henrik Enderlein, who is now ajunior professor at the FreeUniversity of Berlin, comments:“The EMU member states havetried to adapt their economicpolicy institutions to the newsituation – but they have doneso in very different ways.”There are three reasons for this.Firstly, the interplay betweenmonetary, fiscal and wage po-licies in individual countrieswas very different even beforemonetary union. Secondly,there are differences betweenthe structural factors that de-termine whether a country isfaced post-EMU with real in-terest rates that are too low or too high. And finally, thereis also the interplay that hasgrown up over time betweeneconomic policy institutionsand that varies from state tostate. In his study, Enderleindistinguishes between threepatterns of adaptation:

Countries with high realinterest rates and low growthtend to concentrate their at-tempts at reform on fiscal poli-cy because they are unable touse wage policy as a stabilizingfactor; France and Germany fallwithin this category. Especiallyin Germany, the current discus-sions regarding a demand-ori-ented increase in public sector

spending have highlighted an-other problem: the division offiscal policy responsibilities be-tween national and regionalgovernment. In order to over-come the challenges of mone-tary union, the structure ofspending by regional govern-ments and local authorities really ought to be reformed.But centralization is hard toimplement in Germany, wherethe historic roots of federalismrun deep.

For countries with low re-al interest rates and highgrowth, a combination of fiscaland wage policies is the onlysensible course, and both aretherefore being adjusted. Thisapplies, for example, to Ireland,Spain and Portugal, where na-tional stability pacts go hand inhand with greater centraliza-tion of wage policy.

Finally, in those countriesthat were well prepared in ad-vance for monetary union, en-try has had no effect on eco-nomic policy institutions. Thisapplies above all to the Nether-lands, which even beforeEMU had effectively enteredinto monetary union withGermany and had managedwithout a national monetarypolicy since the 1980s.According to Enderlein's study,most countries have initiatedthe necessary reforms. Howev-er, there remain doubts as towhether adaptations at nation-al level will be enough to over-come the problems. ●

Nitrogen, the main compo-nent of air, is normally com-posed of inert molecules inwhich two nitrogen atomsare linked by a triple bond.However, researchers inMikail Eremets’ and ReinhardBoehler’s group at the MaxPlanck Institute for Chem-istry in Mainz have now syn-thesized the first polymeric,cubic nitrogen in which thenitrogen atoms are linked toeach other by single bonds –similar to the carbon atomsin a diamond. This cubic formhad not previously beenfound in any other element,and this polymeric nitrogenpossesses some unique prop-erties, such as an energycontent that is five timesgreater than that of themost powerful non-nuclearexplosives (NATURE MATERIALS,August 2004).

Based on theoretical considera-tions, it had been assumed fortwenty years that single-bondnitrogen must also exist: it wasthought that molecular nitro-gen should transform underhigh pressure to an atomic solidwith a cubic lattice structure.Researchers therefore workedintensively to produce thispolymeric nitrogen, specificallyusing high pressures and differ-

ent temperature ranges. Al-though they found various newnitrogen structures – includinga non-molecular semiconduc-tor phase – they never discov-ered the predicted “nitrogen di-amonds.” Scientists in the high-pressuregroup at the Max Planck Insti-tute for Chemistry in Mainzhave now succeeded in produc-ing this long sought-after poly-meric nitrogen form – by syn-thesizing it from diatomic ni-trogen at temperatures of morethan 2,000 degrees Kelvin andpressures of more than 110 gi-gapascals (corresponding to 1.1million atmospheres). To dothis, the researchers used anew, laser-heated diamondhigh-pressure cell. Analyses ofthe transparent crystal “forcedinto existence” in this way con-firmed that it was indeed poly-meric nitrogen with the theo-retically predicted cubic latticestructure, which is characteris-tic of solids with strong cova-lent bonds. “That is why we callit nitrogen diamond,” saysMikail Eremets, one of theMainz-based Max Planck re-searchers.In contrast to diatomic nitro-gen, which is extremely inertdue to its highly stable triplebond, this polymer, with its sin-gle nitrogen bonds, possesses

Schematic cross-section of a dia-mond anvil cell:The beam of an

infrared laserheats the sample,

while an argonion laser servesto excite a ruby

for spectroscopicpressure mea-

surement.

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Further information from:

CHRISTEL SCHOMMERTZ

(PRESS OFFICE)Max Planck Institutefor the Study ofSocieties, CologneTel.: +49-221 2767-130Fax: +49-2212767-555e-mail: info@mpifg.de

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STUDY OF SOCIETIES

Demand Management Policies Back in Favor?

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