An electron and an electron hole that are attracted to each other by the Coulomb force can form a bound state called an exciton. It is an electrically neutral quasiparticle that exists mainly in condensed matter,including insulators,semiconductors,some metals,but also in certain atoms,molecules and liquids. The exciton is regarded as an elementary excitation that can transport energy without transporting net electric charge.
Photoluminescence is light emission from any form of matter after the absorption of photons. It is one of many forms of luminescence and is initiated by photoexcitation,hence the prefix photo-. Following excitation,various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary:ranging from short femtosecond-regime for emission involving free-carrier plasma in inorganic semiconductors up to milliseconds for phosphoresence processes in molecular systems;and under special circumstances delay of emission may even span to minutes or hours.
Juhan Parts ( is an Estonian politician who was Prime Minister of Estonia from 2003 to 2005 and Minister of Economic Affairs and Communications from 2007 to 2014. Juhan Parts is a member of Isamaa party.
The Estonian Reform Party is a liberal political party in Estonia. The party has been led by Kristen Michal since 2024. It is colloquially known as the "Squirrel Party",referencing its logo.
The Pro Patria Union was a national-conservative political party in Estonia. The party was founded on 2 December 1995 from a merger of the Estonian National Independence Party and the Pro Patria National Coalition.
Rein Lang is an Estonian politician,a member of the Estonian Reform Party since 1995,and a diplomat. He was the Minister of Culture in Andrus Ansip's third cabinet until his resignation.
Mart Laar is an Estonian politician and historian. He served as the Prime Minister of Estonia from 1992 to 1994 and from 1999 to 2002. Laar is credited with having helped bring about Estonia's rapid economic development during the 1990s. He is a member of the centre-right Isamaa party.
Ken-Marti Vaher is a leading member of the Estonian Pro Patria and Res Publica Union party.
Andrus Ansip is an Estonian politician,a member of the European Parliament,the former European Commissioner for Digital Single Market and Vice President of the European Commission,in office from 2014 until 2019. Previously,he was Prime Minister of Estonia from 2005 to 2014 and chairman of the liberal Estonian Reform Party from 2004 to 2014.
Tõnis Lukas is an Estonian politician,former Minister of Culture from 2019 to 2021 and Minister of Education and Research from 1999 to 2002 and from 2007 to 2011.
Ene Ergma is an Estonian politician,a member of the Riigikogu,and scientist. She was a member of the political party Union of Pro Patria and Res Publica and,before the two parties merged,a member of Res Publica Party. On 1 June 2016,Ergma announced her resignation from the party,because the party had lost its identity and turned populist.
The following is an alphabetical list of articles related to the Republic of Estonia.
Siim Valmar Kiisler is an Estonian politician,a member of the Parempoolsed,former member of Isamaa.
Jaak Juske is an Estonian journalist,historian,author,politician,and member of the Social Democratic Party of Estonia.
Urmas Reinsalu is an Estonian politician who served as Minister of Foreign Affairs from 2022 to 2023 and previously from 2019 to 2021. Before that,Urmas has served as the Minister of Defence between 2012 and 2014,and Minister of Justice from 2015 to 2019. Reinsalu is a member and current leader of the Isamaa ("Fatherland") political party,and was the party leader from 2012 to 2015.
Margus Tsahkna is an Estonian politician,leader of new liberal Estonia 200 party since 19 November 2023,former leader of the conservative Isamaa party,former Minister of Defence in Jüri Ratas' cabinet and Minister of Social Protection in Taavi Rõivas' second cabinet. He was sworn in as Minister of Foreign Affairs in the third cabinet of Kaja Kallas on 17 April 2023.
The semiconductor luminescence equations (SLEs) describe luminescence of semiconductors resulting from spontaneous recombination of electronic excitations,producing a flux of spontaneously emitted light. This description established the first step toward semiconductor quantum optics because the SLEs simultaneously includes the quantized light–matter interaction and the Coulomb-interaction coupling among electronic excitations within a semiconductor. The SLEs are one of the most accurate methods to describe light emission in semiconductors and they are suited for a systematic modeling of semiconductor emission ranging from excitonic luminescence to lasers.
Urve Tiidus is an Estonian politician,member of the Reform Party and former journalist. She was Minister of Culture in Taavi Rõivas's first cabinet. She has been a member of Riigikogu since 2011. Before that she served as the mayor of Kuressaare.
Endel Lippmaa was an Estonian scientist,academician,politician,and twice government minister in 1990–1991 and 1995–1996.
An indirect election took place in Estonia on 30 and 31 August 2021 to elect the president of Estonia,who is the country's head of state. The Riigikogu —the Parliament of Estonia —elected Alar Karis to serve in the office and he was sworn in as the 6th president on 11 October 2021. The incumbent,Kersti Kaljulaid,was eligible to seek reelection to a second,and final,term but failed to gain the endorsement of at least 21 MPs,which is required in order for a candidate to register,as she was outspoken against some of the policies of the government,who thus denied her support.
