At a shorter time interval

2002/10/24 Roa Zubia, Guillermo - Elhuyar Zientzia

• Fisika
• Kimika

In a crypton atom, the jump from one electron from one orbital to another requires 24 attoseconds, although this data is not important.

What has been measured for?

Will it have application? Yes. It will have application, but what is most interesting to scientists is that the first experiment of attoseconds has been carried out, that is, the capacity to measure has been improved. The path of attophysics has been opened. What is that?

Let's analyze the time intervals.

A train needs hours to go from Biarritz to Paris, the range is measured in hours. It is known that the fastest train can travel in about four hours. However, from Eibar to Durango a car only needs minutes. In this case we are analyzing the interval in minutes. The actions measured in seconds are also evident, for example, athletes perform a race of 100 meters around 10 seconds. But what processes occur in shorter times?

In this race of 100 meters, the judges use chronometers measuring tenths of a second and hundredths of a second for almost all cases in which two athletes reach the goal.

One-thousandth part of the second

All of them are processes that are easily identified in normal life, but other processes that take place in shorter periods of time are also common. For example, in accidents, the car airbags are inflated in a few milliseconds. Of course, so it must be, because the inflation process must be faster than the movement of the passengers. In fact, there is a chemical reaction inside the airbag, in which the resulting product is gas, so it is inflated. This chemical reaction occurs in milliseconds, that is, in a second the reaction can occur almost a thousand times.

Other processes are given in microseconds. The microsecond is the million of a second, a very short interval. The microprocessor of a computer receives a few microseconds to perform a logical operation. In fact, many of the computers currently on sale work at a speed of 1 gigahercia. This means that in a second they perform a million operations, each of which occurs in several microseconds.

The time the computer takes to read the information of memory chips is measured in nanoseconds, which in a second can read a billion data.

Molecules and atoms

The water molecules move faster than that. In a container the water molecules move constantly and collide with each other. If we wanted to measure the speed of a molecule, we would need a chronometer that measures the picoseconds, that is, the billions of seconds.

But water molecules have another movement faster. In a second, the connections between hydrogen and oxygen vibrate approximately one billion times. This very small time interval is called femtosecond and the branch of chemistry that studies the processes that occur in that interval, femtokimika. The 1999 Nobel Prize in Chemistry was received by the Egyptian Ahmed Zewail for his experiments in the field of femtokimics. Zewail was able to detect different structures that are created and broken down in this period.

Now he plays the attosecond. M. M. In an experiment carried out by the German team Drescher, they have been able to measure for how long the change of state of an electron occurs. In a second, electrons have time to undergo a trilioid state change. To measure this, pulses of XUV radiation between X-rays and ultraviolet rays have been used; unlike what happens in femtokimica, lasers made with visible light do not reach these resolutions.

This new tool analyzes the processes that occur in attosegudos. And these are not within the scope of femtokimika, but within attophysics.