CN1687762A - X ray spectrometer with ultra fast temporal resolution - Google Patents

Abstract

This is a kind of ultra-fast X-Ray-recognizing spectrograph, including the femtosecond laser. The characteristics are that a beam analyzer is set on the laser-output beam path of the femtosecond laser. The reflected light of the beam analyzer will reach the sample workpiece through the optical delay line to form the active light of the sample. The transmitted light of the beam analyzer will go to the photocathode X-Ray diode, and the X-Ray from the diode will go to the sample, detecting the process of the instant structure changing coursed by the active light. Then the X-Ray will go to monocrystalline silicon, and the spectral dispersion coursed by that will be absorbed by the detector. To sum up, this invention can be used to research the light spectrum's changing process coursed by the instant structure changing of the sample.

Description

X ray spectrometer with ultra fast temporal resolution

Technical field

The relevant X ray spectrometer of the present invention particularly relates to a kind of X ray spectrometer with ultra fast temporal resolution, and it has a wide range of applications in fields such as material science, information optics, biological chemistries, and temporal resolution can reach picosecond magnitude.

Background technology

The detection of X ray spectrum is with the visible spectrum detection is the same usually, all on spectrometer, carry out, be based on X ray intrinsic wave characteristic, according to the different dispersion elements that adopted, it is divided into grating spectrometer and crystal spectrometer two big classes, grating spectrometer can be divided into transmission-type and reflective two classes again, and crystal spectrometer mainly is used in the hard X ray zone.

Crystal spectrometer utilizes the atom lattice in the crystal to carry out spectral analysis, and its principle of work is based on the diffraction cloth loudspeaker lattice formula of crystal to X ray:

2dsinθ＝nλ (1)

D is the interplanar distance of crystal, and θ is the angle of diffraction of crystal face, and n is that the order of diffraction is inferior, and λ is a wavelength.The important parameter of crystal spectrometer is spectral resolution, angular dispersion and linear dispersion.With (1) formula two ends differential, promptly get the angular dispersion rate:

$D_{\mathrm{\θ}}=\frac{\mathrm{d\λ}}{\mathrm{d\θ}}=\frac{2d}{n}\cos \mathrm{\θ}=\mathrm{\λctg\θ}---\left(2\right)$

Linear dispersion:

$D_x=\frac{\mathrm{d\λ}}{\mathrm{d\θ}}\frac{\mathrm{d\θ}}{\mathrm{dx}}=D_{\mathrm{\θ}}\frac{\mathrm{d\θ}}{\mathrm{dx}}---\left(3\right)$

In the formula, x is the coordinate on record plane, and spectrometer resolution is:

$R=\frac{\mathrm{\λ}}{\mathrm{\Δ}{\mathrm{\λ}}_{\min }}=\frac{\mathrm{\λ}}{D_{\mathrm{\θ}}{\mathrm{\δ}}_{\mathrm{\θ}}+D_x{\mathrm{\δ}}_x}---\left(4\right)$

In the formula, δ _θBe the half width of crystal diffraction intensity distributions, δ _xFor depending on the response function width of instrument geometric factor.

Crystal spectrometer can be divided into two types, and a kind of is non-focus type, and another kind is the focus type crystal spectrometer.Non-focusing type crystal spectrometer comprises two kinds of optical flat spectrometer and protruding brilliant spectrometers.The available figure below of the classification of crystal spectrometer is represented:

We are interested to be reflective optical flat spectrometer, and principle as shown in Figure 1.

This spectrometer is made up of 4 parts: x-ray source 1, slit 13, chromatic dispersion crystal 10 and detector 11.The X ray that sends from x-ray source records X-ray spectrum after crystalline dispersion, be detected device CCD and receive, and this spectrometer dispersion rate is:

$D_x=\frac{\mathrm{\λ}}{a+b}\mathrm{ctg\θ}---\left(5\right)$

Resolution is:

$R=\frac{\mathrm{\λ}}{D_{x}r}=\frac{a+b}{r}\mathrm{ctg\θ}---\left(6\right)$

In the formula, a is the distance of light source to crystal face, and b is the distance from the crystal face to the recording medium, and r is the lateral dimension of light source.From formula (2) as can be seen: for improving the resolution of spectrometer, must increase apart from a+b, and will that is to say with near 90 ° of glancing angle work, selective value is near the crystal of tested X ray wavelength.This X ray spectrometer is static spectrometer, can not be used for studying the transient state spectrum change.

Summary of the invention:

The technical problem to be solved in the present invention is at the existing shortcoming of above-mentioned technology formerly, and a kind of X ray spectrometer of Superfast time resolution is provided, in order to measure the variation of transient state spectrum.

Technical solution of the present invention is as follows:

A kind of X ray spectrometer with ultra fast temporal resolution, comprise femto-second laser, it is characterized in that on the laser output light path of described femto-second laser, settling a beam splitter, the reflected light of this beam splitter arrives sample via optical delay line, formation is to the effect light beam of sample, transmitted light at this beam splitter is incident on the photocathode x-ray diode through completely reflecting mirror, the X ray that this photocathode x-ray diode produces incides on the sample, detection effect light beam produces the process that transient buildup changes, be incident on the silicon single crystal then, the spectral dispersion that produces is detected device and receives, and shows on computers.

Described femto-second laser is a ti sapphire laser that radiation wavelength is 800nm, and pulsewidth is that 100～1500 femtoseconds, output energy are 0.8～8 millijoule, and 1/10 energy is used for pump light negative electrode x-ray diode.

Described beam splitter be one to 800nm reflection 90%, see through 10% medium lamina membranacea, its host material is quartzy.

Described optical delay line is made of four completely reflecting mirrors.

Described catoptron all is a metal lamina membranacea gold-plated, that 800nm had 100% reflectivity.

Described photocathode x-ray diode is a diode that comprises four ingredients, and promptly photocathode material is an aluminium, and anode material is a tungsten, and sheathing material is quartzy, and it is 800nm thoroughly, and pumping high vacuum seals in the shell, adds the high-voltage power supply of 50～120kV.

Said sample is solid or the liquid that is used for producing fast process, and for example, after being excited by femtosecond pulse, it can produce transient buildup and changes, and we study this process exactly.

Said silicon single crystal is used for producing the X ray dispersion spectrum.

Said detector is to be used for surveying the photocathode x-ray diode through after the sample, contains the image that multidate information became of sample.

Said computing machine is to be used for showing image information received on the detector.

Technique effect of the present invention

The present invention adopts a ti sapphire laser to carry out beam splitting, wherein a branch of effect light beam that is used for, produce a fast process, as incident to be measured, another bundle is used for producing the X ray pulse, as detecting light beam, and uses the light beam lag line between effect light beam and the detecting light beam, be used to adjust light beam and postpone, can survey fast process easily like this.Owing to apply a high voltage on the photocathode x-ray diode, can will get X ray on the anode, this is difficult to obtain on laser plasma.

The present invention compares with technology formerly:

X ray spectrometer with ultra fast temporal resolution of the present invention, owing to adopt same laser instrument work effect light beam and pump beam, can control lag, take fast process, the transient buildup that can be used to study testing sample changes the spectrum change that causes.

Description of drawings

Fig. 1 is the employed X ray optical flat of technology spectrometer structured flowchart formerly.

Fig. 2 is an X ray spectrometer with ultra fast temporal resolution structured flowchart of the present invention.

Embodiment

See also Fig. 2 earlier, Fig. 2 is an X ray spectrometer with ultra fast temporal resolution structured flowchart of the present invention.As seen from the figure, X ray spectrometer with ultra fast temporal resolution of the present invention, comprise femto-second laser 1, on the laser output light path of this femto-second laser 1, settle a beam splitter 2, the folded light beam A of this beam splitter 2 arrives sample 9 via optical delay line, formation is to the effect light beam of sample 9, transmitted light beam B at this beam splitter 2 is incident on the photocathode x-ray diode 8 through completely reflecting mirror 3, the X ray that this photocathode x-ray diode 8 produces incides on the sample 9, detection effect light beam A produces the process that transient buildup changes, be incident on then on the silicon single crystal 10, the spectral dispersion of generation is detected device 11 and receives, and is presented on the computing machine 12.

Described femto-second laser 1 is a ti sapphire laser that radiation wavelength is 800nm, and pulsewidth is that 100～1500 femtoseconds, output energy are 0.8～8 millijoule, and 1/10 energy is used for pump light negative electrode x-ray diode 8.

Described beam splitter 2 be one to 800nm reflection 90%, see through 10% medium lamina membranacea, its host material is quartzy.

Described optical delay line is made of four completely reflecting mirrors 4,5,6,7

Described completely reflecting mirror all is a metal lamina membranacea gold-plated, that 800nm had 100% reflectivity.

Said photocathode x-ray diode 8 is devices that are used for producing X ray, and it is made up of four parts:

Anode 81, material are metals, when photoelectron is beaten on metal, can produce X ray.

Negative electrode 82, material are aluminium, plus high-pressure source 83, and operating voltage is 100kV, shell 84, pumping high vacuum in the shell, the saturating 800nm of sheathing material has the window of a hard X ray on the shell.

Said sample 9 is the solid samples that are used for producing fast process.

Said silicon single crystal 10 is used for the X ray chromatic dispersion, and this is the spectrometer core component, and its dispersive power and resolution are determined by formula (5) and (6).

Said detector 11 is CCD charge-coupled devices, and it can be to the X ray spectrum sensitive.

Said computing machine 12 is the devices that are used for storing and showing the image that obtains on the detector.

The principle of work and the basic process of X ray spectrometer with ultra fast temporal resolution of the present invention are as follows:

The present invention adopts a ti sapphire laser 1 to carry out beam splitting, wherein a branch of (account for total intensity 9/10) is used for the effect light beam, and radiation produces the fast process of laser and matter interaction on sample to be studied 9, as dynamic event to be measured.Another bundle is used for producing photoelectron, produce the X ray pulse as detecting light beam, survey above-mentioned dynamic event, and the delay between two light beams, realize by the light beam lag line, therefore, can realize the synchronous and delay between two light beams easily, by adjusting lag line, just can measure Different Dynamic transient buildup constantly and change.

Owing to adopt photoelectron, its monochromaticity can be controlled by the live width of control titanium precious stone laser, because the anode in the photocathode x-ray diode adopts metal, the X ray of emission is that laser plasma is far inaccessiable.

After the photo of noting first Superfast time resolution X-ray spectrum, postpone 10ps, repeat above-mentioned experiment, take one again, continuous like this is a step with 10ps, repeats, photograph till the above-mentioned dynamic event end, its time resolution is picosecond magnitude always.

Claims (6)

1, a kind of X ray spectrometer with ultra fast temporal resolution, comprise femto-second laser (1), it is characterized in that on the laser output light path of described femto-second laser (1), settling a beam splitter (2), the reflected light of this beam splitter (2) arrives sample (9) via optical delay line, formation is to the effect light beam (A) of sample (9), transmitted light (B) in this beam splitter (2) is incident on the photocathode x-ray diode (8) through completely reflecting mirror (3), the X ray that this photocathode x-ray diode (8) produces incides on the sample (9), detection effect light beam (A) produces the process that transient buildup changes, be incident on then on the silicon single crystal (10), the spectral dispersion that is produced is detected device (11) and receives, and is presented on the computing machine (12).

2, X ray spectrometer with ultra fast temporal resolution according to claim 1, it is characterized in that described femto-second laser (1) is a ti sapphire laser that radiation wavelength is 800nm, pulsewidth is that 100～1500 femtoseconds, output energy are 0.8～8 millijoule, and 1/10 energy is used for pump light negative electrode x-ray diode (8).

3, X ray spectrometer with ultra fast temporal resolution according to claim 1, it is characterized in that described beam splitter (2) be one to 800nm reflection 90%, see through 10% medium lamina membranacea, its host material is quartzy.

4, X ray spectrometer with ultra fast temporal resolution according to claim 1 is characterized in that described optical delay line is made of four completely reflecting mirrors (4,5,6,7).

5, X ray spectrometer with ultra fast temporal resolution according to claim 4 is characterized in that described catoptron all is a metal lamina membranacea gold-plated, that 800nm had 100% reflectivity.

6, according to each described X ray spectrometer with ultra fast temporal resolution of claim 1 to 5, it is characterized in that described photocathode x-ray diode (8) is a diode that comprises four ingredients, be that photocathode material is an aluminium, anode material is a tungsten, sheathing material is quartzy, it is 800nm thoroughly, and pumping high vacuum seals in the shell, adds the high-voltage power supply of 50～120kV.

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