Re: [Ifeffit] Brain teaser

[Anatoly Frenkel]

HI Mike, it is dilute Pd in Au nanoparticles deposited on SiO2 with about
5% metal weight loading.
In my view, the lack of curvature in transmission (the original problem in
my post) is a simple consequence of two opposite trends, 1) the curving up
of the transmission signal by the same reason (yet to be identified, which
is something I will try to, after getting useful hints from many people
here) as the curving up of the incident beam and 2) the opposite trend due
to the greater removal of the photons at higher energy by I0 detector. The
two opposite trends tend to cancel each other.

Anatoly



On Thu, Jun 15, 2023 at 4:14 PM Mike Massey  wrote:

> A question because I'm not really super clear on how harmonics work:
>
> (I'll get to the question in a moment...) I note that I0 starts to go
> non-linear around 12200-12400 eV and stays that way. So an increase
> (proportional?) in the amount of signal in It might be happening at around
> the same point.
>
> Could Pd fluorescence into It be impacting the signal in It? I realize
> that the Pd emission lines are very low in energy but they are around 3k eV.
>
> I'm not super familiar with alloy systems but I did have an issue once
> upon a time with back fluorescence into an ion chamber and things went a
> bit wonky. This wouldn't exactly be "back" fluorescence, but if the system
> is mostly Pd with a little bit of Au, I guess...? And it might be easy
> enough to test, just put a high-pass filter in front of It?
>
> I got nothin' but it's kinda fun to take a shot. Cheers,
>
>
>
> Mike
>
>
>
>
> On Jun 16, 2023, at 03:26, Matt Newville 
> wrote:
>
> 
> Hi Anatoly,
>
> I think Robert or Matthew made this point, but if set up for Pd, the
> mirror angle may have been chosen to reject ~70 keV, but possibly not 36
> keV -- the harmonic at the Au edge.  Do you know what the mirror angle
> was?
>
> The Ar-filled I0 would be very efficient at absorbing 12 keV, and only
> pretty efficient at absorbing 36 keV.   That would leave a more
> harmonic-rich beam exiting I0 and hitting the sample than entering I0.  The
> good news is that the dense Pd/Au sample would be efficient at absorbing 36
> keV too (but it was ~1 absorption length at 24 keV?) too.
>
> Mono reflectivity of 36 keV vs 12 keV might also factor in.  If you were
> not deliberately detuning but the crystals were slightly misaligned,  the
> harmonic content may change significantly over the scan range.   I would
> not guess that to dominate, but maybe it factors in.
>
>
> On Thu, Jun 15, 2023 at 9:54 AM Anatoly Frenkel <
> anatoly.fren...@stonybrook.edu> wrote:
>
>> Thank you, Matt.
>> Ion chambers were filled with 90% Ar, and Pt coating was used, because we
>> were measuring Pd K edge for the project, but we decided to look at the Au
>> edge for testing purposes.
>>
>> Anatoly
>>
>> On Jun 15, 2023, at 10:45 AM, Matt Newville 
>> wrote:
>>
>> 
>> I'm not sure why the intensity would go up unless the ion chamber was
>> poorly set up.   But, as others have pointed out, the mirror reflectivity
>> for a Pt mirror should not change significantly over this energy range -
>> the energy range is not that close to the Pt L3 or L2 edges.Depending
>> on where it was located, fluorescence from the Pt mirror might pollute the
>> signal in the I0 ion chamber, but that would also likely be a fairly
>> constant background.
>>
>> But, why would you fill the I0 ion chamber with Argon?  A 10-cm ion
>> chamber filled with Ar would absorb about 50% of the beam at 12 keV.   Even
>> at 24 keV, that would absorb 8% of the beam - not necessarily a problem but
>> also probably generating at least a micro-Amp, so way more signal than you
>> would need.
>>
>> For mirror reflectivity curves, allow me to humbly remind everyone of
>>
>> https://xraydb.xrayabsorption.org/reflectivity/Pt/21.45/2.5/10/s/1000/51000/50/platinum/linear
>>
>> which is both interactive and works with X-ray energies above 30 keV.
>>
>>
>> On Wed, Jun 14, 2023 at 7:28 PM Anatoly Frenkel <
>> anatoly.fren...@stonybrook.edu> wrote:
>>
>>> Hello, all. It is a low- to medium- level brain teaser.
>>>
>>> Pt-coated collimating mirror was in place for Pd K-edge measurement, but
>>> Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It
>>> detectors were both Ar filled ionization chambers. Because of the energy
>>> dependence of reflectivity of the Pt mirror, I0 intensity was strongly
>>> nonlinear (blue curve). However, the transmission intensity in the It
>>> detector was almost linear (red curve). Why?
>>>
>>> Anatoly
>>>
>>> 
>>>
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>>
>>
>> --
>> --Matt Newville  630-327-7411
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>> 

Re: [Ifeffit] Brain teaser

[Mike Massey]

A question because I'm not really super clear on how harmonics work: (I'll get to the question in a moment...) I note that I0 starts to go non-linear around 12200-12400 eV and stays that way. So an increase (proportional?) in the amount of signal in It might be happening at around the same point.Could Pd fluorescence into It be impacting the signal in It? I realize that the Pd emission lines are very low in energy but they are around 3k eV.I'm not super familiar with alloy systems but I did have an issue once upon a time with back fluorescence into an ion chamber and things went a bit wonky. This wouldn't exactly be "back" fluorescence, but if the system is mostly Pd with a little bit of Au, I guess...? And it might be easy enough to test, just put a high-pass filter in front of It?I got nothin' but it's kinda fun to take a shot. Cheers,MikeOn Jun 16, 2023, at 03:26, Matt Newville  wrote:Hi Anatoly, I think Robert or Matthew made this point, but if set up for Pd, the mirror angle may have been chosen to reject ~70 keV, but possibly not 36 keV -- the harmonic at the Au edge.  Do you know what the mirror angle was?    The Ar-filled I0 would be very efficient at absorbing 12 keV, and only pretty efficient at absorbing 36 keV.   That would leave a more harmonic-rich beam exiting I0 and hitting the sample than entering I0.  The good news is that the dense Pd/Au sample would be efficient at absorbing 36 keV too (but it was ~1 absorption length at 24 keV?) too.Mono reflectivity of 36 keV vs 12 keV might also factor in.  If you were not deliberately detuning but the crystals were slightly misaligned,  the harmonic content may change significantly over the scan range.   I would not guess that to dominate, but maybe it factors in.On Thu, Jun 15, 2023 at 9:54 AM Anatoly Frenkel  wrote:Thank you, Matt. Ion chambers were filled with 90% Ar, and Pt coating was used, because we were measuring Pd K edge for the project, but we decided to look at the Au edge for testing purposes. AnatolyOn Jun 15, 2023, at 10:45 AM, Matt Newville  wrote:I'm not sure why the intensity would go up unless the ion chamber was poorly set up.   But, as others have pointed out, the mirror reflectivity for a Pt mirror should not change significantly over this energy range - the energy range is not that close to the Pt L3 or L2 edges.    Depending on where it was located, fluorescence from the Pt mirror might pollute the signal in the I0 ion chamber, but that would also likely be a fairly constant background. But, why would you fill the I0 ion chamber with Argon?  A 10-cm ion chamber filled with Ar would absorb about 50% of the beam at 12 keV.   Even at 24 keV, that would absorb 8% of the beam - not necessarily a problem but also probably generating at least a micro-Amp, so way more signal than you would need.For mirror reflectivity curves, allow me to humbly remind everyone of   https://xraydb.xrayabsorption.org/reflectivity/Pt/21.45/2.5/10/s/1000/51000/50/platinum/linearwhich is both interactive and works with X-ray energies above 30 keV.On Wed, Jun 14, 2023 at 7:28 PM Anatoly Frenkel  wrote:Hello, all. It is a low- to medium- level brain teaser.Pt-coated collimating mirror was in place for Pd K-edge measurement, but Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It detectors were both Ar filled ionization chambers. Because of the energy dependence of reflectivity of the Pt mirror, I0 intensity was strongly nonlinear (blue curve). However, the transmission intensity in the It detector was almost linear (red curve). Why? Anatoly
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Re: [Ifeffit] Brain teaser

[Matt Newville]

Hi Anatoly,

I think Robert or Matthew made this point, but if set up for Pd, the mirror
angle may have been chosen to reject ~70 keV, but possibly not 36 keV --
the harmonic at the Au edge.  Do you know what the mirror angle was?

The Ar-filled I0 would be very efficient at absorbing 12 keV, and only
pretty efficient at absorbing 36 keV.   That would leave a more
harmonic-rich beam exiting I0 and hitting the sample than entering I0.  The
good news is that the dense Pd/Au sample would be efficient at absorbing 36
keV too (but it was ~1 absorption length at 24 keV?) too.

Mono reflectivity of 36 keV vs 12 keV might also factor in.  If you were
not deliberately detuning but the crystals were slightly misaligned,  the
harmonic content may change significantly over the scan range.   I would
not guess that to dominate, but maybe it factors in.


On Thu, Jun 15, 2023 at 9:54 AM Anatoly Frenkel <
anatoly.fren...@stonybrook.edu> wrote:

> Thank you, Matt.
> Ion chambers were filled with 90% Ar, and Pt coating was used, because we
> were measuring Pd K edge for the project, but we decided to look at the Au
> edge for testing purposes.
>
> Anatoly
>
> On Jun 15, 2023, at 10:45 AM, Matt Newville 
> wrote:
>
> 
> I'm not sure why the intensity would go up unless the ion chamber was
> poorly set up.   But, as others have pointed out, the mirror reflectivity
> for a Pt mirror should not change significantly over this energy range -
> the energy range is not that close to the Pt L3 or L2 edges.Depending
> on where it was located, fluorescence from the Pt mirror might pollute the
> signal in the I0 ion chamber, but that would also likely be a fairly
> constant background.
>
> But, why would you fill the I0 ion chamber with Argon?  A 10-cm ion
> chamber filled with Ar would absorb about 50% of the beam at 12 keV.   Even
> at 24 keV, that would absorb 8% of the beam - not necessarily a problem but
> also probably generating at least a micro-Amp, so way more signal than you
> would need.
>
> For mirror reflectivity curves, allow me to humbly remind everyone of
>
> https://xraydb.xrayabsorption.org/reflectivity/Pt/21.45/2.5/10/s/1000/51000/50/platinum/linear
>
> which is both interactive and works with X-ray energies above 30 keV.
>
>
> On Wed, Jun 14, 2023 at 7:28 PM Anatoly Frenkel <
> anatoly.fren...@stonybrook.edu> wrote:
>
>> Hello, all. It is a low- to medium- level brain teaser.
>>
>> Pt-coated collimating mirror was in place for Pd K-edge measurement, but
>> Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It
>> detectors were both Ar filled ionization chambers. Because of the energy
>> dependence of reflectivity of the Pt mirror, I0 intensity was strongly
>> nonlinear (blue curve). However, the transmission intensity in the It
>> detector was almost linear (red curve). Why?
>>
>> Anatoly
>>
>> 
>>
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>
>
> --
> --Matt Newville  630-327-7411
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Re: [Ifeffit] Brain teaser

[Anatoly Frenkel]

Thank you, Matt. Ion chambers were filled with 90% Ar, and Pt coating was used, because we were measuring Pd K edge for the project, but we decided to look at the Au edge for testing purposes. AnatolyOn Jun 15, 2023, at 10:45 AM, Matt Newville  wrote:I'm not sure why the intensity would go up unless the ion chamber was poorly set up.   But, as others have pointed out, the mirror reflectivity for a Pt mirror should not change significantly over this energy range - the energy range is not that close to the Pt L3 or L2 edges.    Depending on where it was located, fluorescence from the Pt mirror might pollute the signal in the I0 ion chamber, but that would also likely be a fairly constant background. But, why would you fill the I0 ion chamber with Argon?  A 10-cm ion chamber filled with Ar would absorb about 50% of the beam at 12 keV.   Even at 24 keV, that would absorb 8% of the beam - not necessarily a problem but also probably generating at least a micro-Amp, so way more signal than you would need.For mirror reflectivity curves, allow me to humbly remind everyone of   https://xraydb.xrayabsorption.org/reflectivity/Pt/21.45/2.5/10/s/1000/51000/50/platinum/linearwhich is both interactive and works with X-ray energies above 30 keV.On Wed, Jun 14, 2023 at 7:28 PM Anatoly Frenkel  wrote:Hello, all. It is a low- to medium- level brain teaser.Pt-coated collimating mirror was in place for Pd K-edge measurement, but Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It detectors were both Ar filled ionization chambers. Because of the energy dependence of reflectivity of the Pt mirror, I0 intensity was strongly nonlinear (blue curve). However, the transmission intensity in the It detector was almost linear (red curve). Why? Anatoly
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Re: [Ifeffit] Brain teaser

[Matt Newville]

I'm not sure why the intensity would go up unless the ion chamber was
poorly set up.   But, as others have pointed out, the mirror reflectivity
for a Pt mirror should not change significantly over this energy range -
the energy range is not that close to the Pt L3 or L2 edges.Depending
on where it was located, fluorescence from the Pt mirror might pollute the
signal in the I0 ion chamber, but that would also likely be a fairly
constant background.

But, why would you fill the I0 ion chamber with Argon?  A 10-cm ion chamber
filled with Ar would absorb about 50% of the beam at 12 keV.   Even at 24
keV, that would absorb 8% of the beam - not necessarily a problem but also
probably generating at least a micro-Amp, so way more signal than you would
need.

For mirror reflectivity curves, allow me to humbly remind everyone of

https://xraydb.xrayabsorption.org/reflectivity/Pt/21.45/2.5/10/s/1000/51000/50/platinum/linear

which is both interactive and works with X-ray energies above 30 keV.


On Wed, Jun 14, 2023 at 7:28 PM Anatoly Frenkel <
anatoly.fren...@stonybrook.edu> wrote:

> Hello, all. It is a low- to medium- level brain teaser.
>
> Pt-coated collimating mirror was in place for Pd K-edge measurement, but
> Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It
> detectors were both Ar filled ionization chambers. Because of the energy
> dependence of reflectivity of the Pt mirror, I0 intensity was strongly
> nonlinear (blue curve). However, the transmission intensity in the It
> detector was almost linear (red curve). Why?
>
> Anatoly
>
> [image: image.png]
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Re: [Ifeffit] Brain teaser

[Kirill LOMACHENKO]

Hi Anatoly,

maybe the high voltage of the I0 chamber is off?

All the best,
Kirill


Dr. Kirill A. Lomachenko
Scientist at BM23/ID24 beamlines
European Synchrotron Radiation Facility
71 avenue des Martyrs
CS 40220
38043 Grenoble Cedex 9, France
Tel: +33 438 88 19 14
www.esrf.eu

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Today's Topics:

1. Re: Brain teaser (Anatoly Frenkel)
2. Re: [Ext]  Brain teaser (Jeffrey Terry)
3. Re: [Ext] Brain teaser (matthew marcus)


--

Message: 1
Date: Thu, 15 Jun 2023 00:30:41 -0400
From: Anatoly Frenkel 
To: XAFS Analysis using Ifeffit 
Subject: Re: [Ifeffit] Brain teaser
Message-ID: <866eaccf-dad2-4486-aae0-ac3f6b280...@stonybrook.edu>
Content-Type: text/plain; charset=utf-8

Amazing idea. I thunk you were the only one who succeeded to use third harmonic 
of Si for taking EXAFS at high atomic number elements. But that does not 
explain the peaks and dips.

Anatoly


On Jun 15, 2023, at 12:22 AM, matthew marcus  wrote:

?Suppose the mono is being used at the 333 reflection (for Si), intentionally 
working at the 3rd harmonic.  In that case, if the fundamental isn't filtered 
out, you could get just what we see, with the sample doing the filtering before 
the beam gets to the transmission chamber.
mam


On 6/14/2023 9:16 PM, Anatoly Frenkel wrote:
Thank you, Matthew and Robert, but I think the explanation is more simplle. The 
fact that there are peaks in I0 and dips in transmission is a clue that 
explains why transmission is almost linear while I0 curves up.
Anatoly

On Jun 14, 2023, at 11:34 PM, matthew marcus  wrote:

?One thing that's pretty odd is that the glitches are peaks in I0, and dips in 
It.  It would be much easier to explain if It was the one that increased 
steeply and I0 was more linear, but the presence of the edge in It shows that 
you didn't switch them.  Red = It.  What's that sudden drop at the end?

Could it be that the I0 chamber is misaligned so that beam is scraping one of 
the plates?  That could cause all sorts of odd things to happen.
mam


On 6/14/2023 5:27 PM, Anatoly Frenkel wrote:
Hello, all. It is a low- to medium- level brain teaser.
Pt-coated collimating mirror was in place for Pd K-edge measurement, but Au 
L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It detectors 
were both Ar filled ionization chambers. Because of the energy dependence of 
reflectivity of the Pt mirror, I0 intensity was strongly nonlinear (blue 
curve). However, the transmission intensity in the It detector was almost 
linear (red curve). Why?
Anatoly
image.png
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--

Message: 2
Date: Thu, 15 Jun 2023 00:17:35 -0500
From: Jeffrey Terry 
To: XAFS Analysis using Ifeffit 
Subject: Re: [Ifeffit] [Ext]  Brain teaser
Message-ID: 
Content-Type: text/plain; charset="utf-8"

Well, I?ll take a shot. Looks like the mirror angle is totally fubared, you are 
getting Bragg peaks from the coating or substrate that are giving you the peaks 
in Io. Since you have no idea what angle those are going through Io, they are 
unlikely to make it into either the sample or It. Since those photons are 
removed from the beam hitting the sample, they would show up as intensity dips 
in It. I?d bet that most (all?) of the reflected beam is not going into the 
sample. I?m kind of surprised It signal is as clean as it is, but then I don?t 
know the gains on either measurement amplifie

Re: [Ifeffit] Brain teaser

[Anatoly Frenkel]

Amazing idea. I thunk you were the only one who succeeded to use third harmonic 
of Si for taking EXAFS at high atomic number elements. But that does not 
explain the peaks and dips. 

Anatoly

> On Jun 15, 2023, at 12:22 AM, matthew marcus  wrote:
> 
> Suppose the mono is being used at the 333 reflection (for Si), intentionally 
> working at the 3rd harmonic.  In that case, if the fundamental isn't filtered 
> out, you could get just what we see, with the sample doing the filtering 
> before the beam gets to the transmission chamber.
>mam
> 
>> On 6/14/2023 9:16 PM, Anatoly Frenkel wrote:
>> Thank you, Matthew and Robert, but I think the explanation is more simplle. 
>> The fact that there are peaks in I0 and dips in transmission is a clue that 
>> explains why transmission is almost linear while I0 curves up.
>> Anatoly
 On Jun 14, 2023, at 11:34 PM, matthew marcus  wrote:
>>> 
>>> One thing that's pretty odd is that the glitches are peaks in I0, and dips 
>>> in It.  It would be much easier to explain if It was the one that increased 
>>> steeply and I0 was more linear, but the presence of the edge in It shows 
>>> that you didn't switch them.  Red = It.  What's that sudden drop at the end?
>>> 
>>> Could it be that the I0 chamber is misaligned so that beam is scraping one 
>>> of the plates?  That could cause all sorts of odd things to happen.
>>>mam
>>> 
 On 6/14/2023 5:27 PM, Anatoly Frenkel wrote:
 Hello, all. It is a low- to medium- level brain teaser.
 Pt-coated collimating mirror was in place for Pd K-edge measurement, but 
 Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It 
 detectors were both Ar filled ionization chambers. Because of the energy 
 dependence of reflectivity of the Pt mirror, I0 intensity was strongly 
 nonlinear (blue curve). However, the transmission intensity in the It 
 detector was almost linear (red curve). Why?
 Anatoly
 image.png
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Re: [Ifeffit] Brain teaser

[matthew marcus]

Suppose the mono is being used at the 333 reflection (for Si), 
intentionally working at the 3rd harmonic.  In that case, if the 
fundamental isn't filtered out, you could get just what we see, with the 
sample doing the filtering before the beam gets to the transmission chamber.

mam

On 6/14/2023 9:16 PM, Anatoly Frenkel wrote:

Thank you, Matthew and Robert, but I think the explanation is more simplle. The 
fact that there are peaks in I0 and dips in transmission is a clue that 
explains why transmission is almost linear while I0 curves up.

Anatoly


On Jun 14, 2023, at 11:34 PM, matthew marcus  wrote:

One thing that's pretty odd is that the glitches are peaks in I0, and dips in 
It.  It would be much easier to explain if It was the one that increased 
steeply and I0 was more linear, but the presence of the edge in It shows that 
you didn't switch them.  Red = It.  What's that sudden drop at the end?

Could it be that the I0 chamber is misaligned so that beam is scraping one of 
the plates?  That could cause all sorts of odd things to happen.
mam


On 6/14/2023 5:27 PM, Anatoly Frenkel wrote:
Hello, all. It is a low- to medium- level brain teaser.
Pt-coated collimating mirror was in place for Pd K-edge measurement, but Au 
L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It detectors 
were both Ar filled ionization chambers. Because of the energy dependence of 
reflectivity of the Pt mirror, I0 intensity was strongly nonlinear (blue 
curve). However, the transmission intensity in the It detector was almost 
linear (red curve). Why?
Anatoly
image.png
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Re: [Ifeffit] Brain teaser

[Anatoly Frenkel]

Thank you, Matthew and Robert, but I think the explanation is more simplle. The 
fact that there are peaks in I0 and dips in transmission is a clue that 
explains why transmission is almost linear while I0 curves up. 

Anatoly

> On Jun 14, 2023, at 11:34 PM, matthew marcus  wrote:
> 
> One thing that's pretty odd is that the glitches are peaks in I0, and dips 
> in It.  It would be much easier to explain if It was the one that increased 
> steeply and I0 was more linear, but the presence of the edge in It shows that 
> you didn't switch them.  Red = It.  What's that sudden drop at the end?
> 
> Could it be that the I0 chamber is misaligned so that beam is scraping one of 
> the plates?  That could cause all sorts of odd things to happen.
>mam
> 
>> On 6/14/2023 5:27 PM, Anatoly Frenkel wrote:
>> Hello, all. It is a low- to medium- level brain teaser.
>> Pt-coated collimating mirror was in place for Pd K-edge measurement, but Au 
>> L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It 
>> detectors were both Ar filled ionization chambers. Because of the energy 
>> dependence of reflectivity of the Pt mirror, I0 intensity was strongly 
>> nonlinear (blue curve). However, the transmission intensity in the It 
>> detector was almost linear (red curve). Why?
>> Anatoly
>> image.png
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Re: [Ifeffit] Brain teaser

[matthew marcus]

One thing that's pretty odd is that the glitches are peaks in I0, and 
dips in It.  It would be much easier to explain if It was the one that 
increased steeply and I0 was more linear, but the presence of the edge 
in It shows that you didn't switch them.  Red = It.  What's that sudden 
drop at the end?


Could it be that the I0 chamber is misaligned so that beam is scraping 
one of the plates?  That could cause all sorts of odd things to happen.

mam

On 6/14/2023 5:27 PM, Anatoly Frenkel wrote:

Hello, all. It is a low- to medium- level brain teaser.

Pt-coated collimating mirror was in place for Pd K-edge measurement, but 
Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It 
detectors were both Ar filled ionization chambers. Because of the energy 
dependence of reflectivity of the Pt mirror, I0 intensity was strongly 
nonlinear (blue curve). However, the transmission intensity in the It 
detector was almost linear (red curve). Why?


Anatoly

image.png

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Re: [Ifeffit] Brain teaser

[Robert Gordon]

Hi Anatoly,

reflectivity of Pt over that energy range does not vary that much:

[image: image.png]

I guessed what angle you were set for, assuming Pd K-edge...
So something wrong with I0?

-R.


On Wed, Jun 14, 2023 at 5:28 PM Anatoly Frenkel <
anatoly.fren...@stonybrook.edu> wrote:

> Hello, all. It is a low- to medium- level brain teaser.
>
> Pt-coated collimating mirror was in place for Pd K-edge measurement, but
> Au L3-edge of Pd-Au alloy was measured (for testing purposes). I0 and It
> detectors were both Ar filled ionization chambers. Because of the energy
> dependence of reflectivity of the Pt mirror, I0 intensity was strongly
> nonlinear (blue curve). However, the transmission intensity in the It
> detector was almost linear (red curve). Why?
>
> Anatoly
>
> [image: image.png]
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