РОССИЙСКАЯ АКАДЕМИЯ НАУК

УРАЛЬСКОЕ ОТДЕЛЕНИЕ

ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА
   
| | | | |
| | | |
 11.06.2010   Карта сайта     Language По-русски По-английски
Новые материалы
Экология
Электротехника и обработка материалов
Медицина
Статистика публикаци


11.06.2010


Laser tracks electrons in molecules



09 June 2010



An international team of researchers has used attosecond laser pulses to track the movement of electrons in molecules for the first time. The breakthrough suggests that attosecond lasers will soon enable scientists to address problems in chemistry and biology, which until now were too complex for attosecond science.


At just 10-18 seconds, an attosecond is to one second what one second is to the age of the universe. For almost a decade scientists have been able to create laser pulses this brief, in doing so opening up a new level in atomic probing. Unlike femtosecond pulses, which can only 'freeze' the position of atoms and molecules, attosecond pulses can freeze the position of the orbiting electrons themselves.


Since their development, attosecond laser pulses have been used to investigate a variety of processes, including the exciting and ionisation of atoms, and electron dynamics in solids. Yet so far they haven't been used on molecules, which are more complex. One goal has been to see how electric charge redistributes and how it affects the nuclear movement once a molecule is ionised.


This is exactly what Marc Vrakking of the Max Born Institute for Nonlinear Optics and Short Time Spectroscopy in Berlin, Germany, and colleagues have attempted to do. The team, which includes researchers in Italy, the Netherlands, Germany, Sweden, France, Columbia and the UK, has localised the position of electrons with attosecond resolution within hydrogen - nature's simplest molecule - as it is ionised. 


In the experiments, the researchers fire an ultraviolet attosecond laser pulse at a hydrogen molecule to strip it of one electron, before using an infrared laser to break the molecule in two. By varying the delay between the ultraviolet pulse and the infrared beam, they could build a picture of how the remaining electron moves within the molecular ion left behind, and how both electrons affect the nuclear rearrangement, or splitting. 


Electron dynamics









Electron dynamics in molecular hydrogen following photoionisation by an attosecond laser pulse. The remaining electron in the molecule (depicted in green) is measured experimentally and shown as a mountain landscape. Hills and valleys correspond to a higher probability of finding the electron on the left and right side of the molecule respectively



© Christian Hackenberger



Vrakking and coworkers discovered that the coupling of the electrons to the atoms plays a strong role in the ionisation process. In the past, theory has had to include the so-called Born-Oppenheimer approximation, which effectively says that electrons are so small and fast that they readily adapt to the motion of the atoms - but now scientists will be able to understand how this approximation breaks down. Yet the researchers also found an unanticipated feature: that not just one, but both electrons can become excited before one finally leaves the molecule.


Ferenc Krausz, a leading attosecond physicist at the Max-Planck Institute for Quantum Optics in Garching, Germany, says the work 'constitutes an important milestone in the evolution of attosecond science.'


'Attosecond physics and technology has so far centred on studies of simple - in most cases atomic - systems in which the outcome of the experiment could be safely predicted, with the primary aim of validating the novel methodology,' he adds. '[These] experiments extend the applications of attosecond metrology for the first time to more complex systems.'


Vrakking explains that his group's next goal is to try to repeat the experiment without the infrared laser, which presently does as much to steer the molecule's dynamics as to probe them. 'We couldn't argue that it's been a passive observer,' he says.


Jon Cartwright


 


Interesting? Spread the word using the 'tools' menu on the left.



References


G Sansone et al, Nature, 2010, DOI: 10.1038/nature09084


Дизайн и программирование N-Studio 
А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

  • © 2004-2019 ИХТТ УрО РАН
    беременность, мода, красота, здоровье, диеты, женский журнал, здоровье детей, здоровье ребенка, красота и здоровье, жизнь и здоровье, секреты красоты, воспитание ребенка рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок медицина, клиники и больницы, болезни, врач, лечение, доктор, наркология, спид, вич, алкоголизм православные знакомства, православный сайт творчeства, православные рассказы, плохие мысли, православные психологи рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок