# Is it possible to observe the Li K spectrum of LiF with an electron probe?

Philippe Jonnard

► To cite this version:

Philippe Jonnard. Is it possible to observe the Li K spectrum of LiF with an electron probe?. AMAS XVII, seventeenth Symposium of the Australian Microbeam Analysis Society, Feb 2026, Melbourne (AUS), Australia. hal-05508012

HAL Id: hal-05508012

https://hal.science/hal-05508012v1

Submitted on 12 Feb 2026

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# Is it possible to observe the Li K spectrum of LiF with an electron probe?

P. Jonnard

Laboratoire de Chimie Physique – Matière et Rayonnement
Sorbonne Université – CNRS
Paris, France
## Collaboration

* **ANR "Spectroscopy and quantification of lithium by microanalysis"**

* **LCPMR**

* K. Le Guen

* K. Hassebi

* N. Temmar

* W. Aid

* R. Benbalagh

* R. Vacheresse

* A. Boucly

* **Sorbonne Université**

* N. Rividi

* M. Fialin

* A. Verlaguet

* G. Godard

* B. Dubacq

* O. Boudouma

* W. Bai

* **CEA Marcoule**

* E. Brackx

* P. Schweizer

* **CEA Saclay**

* M.-C. Lépy

* Y. Ménesguen

* **McGill University, Canada**

* R. Gauvin

* N. Brodusch

* **Nano Optics Berlin**

* **Greateyes**
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
Database
# bibliography of x-ray emissions

A bibliographic database of x-ray emissions
as a function of the chemical state of the emitting element
X-Ray Spectrom. 55, 176-183 (2026) doi: 10.1002/xrs.70033
1400 pages – 43000 lines – more than 6000 references

https://hal.science/hal-05408336

<figure><img src="image_2.png" /></figure>

Li Kα
LiF

K. Hassebi

P. Schweizer

M. Terauchi

A.-S. Robbes

P. Hovington

H. Takahashi

R. Rinaldi

H. Takahashi

S. Fukushima

S. Fukushima

K.L. Tsang

T.A. Callcott

K. Tsutsumi

O. Aita

E.T. Arakawa

E.T. Arakawa

A.A. Maiste

M. Elango

XRS 54, 76 (2025)

Spectrochim. Acta B218, 106994 (2024)

JEOL handbook (2021)

Robbes-Goldschmidt (2017)

Scanning 38, 571 (2016)

IOP Conf. Ser. 109, 012017 (2016)

MM 21, 1053 (2015)

Microsc. Anal. S4 (2014)

MM 14S2, 1286 (2008)

MM 12S2, 872 (2006)

PRB 35, 8374 (1987)

RSI 57, 2680 (1986)

ISXRPAS 775 (1981)

PRB 23, 5676 (1981)

PRL 36, 333 (1976)

Phys. Fenn. 9S1, 192 (1974)

JETP Lett. 18, 97 (1973)

VURP74, p.390 (1974)

10.1002/xrs.3427

10.1016/j.sab.2024.106994

See List of journals

10.1002/sca.21302

10.1088/1757-899X/109/1/012017

10.1017/S1431927615000409

https://www.microscopyebooks.com/Asia/Supplements/2014/November/#p=6

10.1017/S1431927608084390

10.1017/S1431927606062453

10.1103/PhysRevB.35.8374

10.1063/1.1139078

10.1007/978-1-4615-9236-5_150

10.1103/PhysRevB.23.5676

10.1103/PhysRevLett.36.333

http://jetpletters.ru/ps/1808/article_27628.shtml

sciences-lcpmr-database@sorbonne-universite.fr

philippe.jonnard@sorbonne-universite.fr
Previous spectra under electron excitation

<figure><img src="image_3.png" /></figure>

JEOL handbook
(2023)

<figure><img src="image_4.png" /></figure>

Takahashi
(2014)

<figure><img src="image_5.png" /></figure>

Fukushima
(2006)

<figure><img src="image_6.png" /></figure>

Hassebi
(2025)

Arakawa (1974)
Previous spectra under x-ray excitation (XRF)

<figure><img src="image_7.png" /><figcaption>Tsang (1987)</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>Arakawa
(1976)</figcaption></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /><figcaption>Callcot (1986)</figcaption></figure>
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
LiF electronic structure

<figure><img src="image_12.png" /></figure>

Arakawa (1976)

“standard” emission band
2p – 1s electron transition
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
Spectroscopy in the Li Kα range, around 50 eV

* Variable line spacing grating or **reflection Fresnel zone plate**

* Flat field spectrometer, **no scanning**

* Detection with a linear detector or **CCD camera**

* Grating law **nλ = d (sinα – sinβ)** d is the period of the grating
α and β are the incident and detection angles

<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /></figure>

<figure><img src="image_15.png" /></figure>
Analysed depths electrons – x-rays

* Generation of Li 1s ionizations (Monte Carlo simulation with McXRay)

<figure><img src="image_16.png" /></figure>

* Attenuation length (CXRO) ≈15 nm
Photons can come from 50 nm at maximum

<figure><img src="image_17.png" /></figure>
Working conditions

* **LiF** Thin slab used to disperse x-rays in crystal spectrometer
  **No coating** (protective or conductive)
  Cleaned aceton, alcohol, CO₂ snow jet

* **1 kV** acceleration voltage
  No more focused beam (spot of a few hundreds µm)
  Degraded spectral resolution (>1 eV)

* **800 nA** current, no regulation
  Low current density around **1 pA/µm²** (800 nA in 1 mm)
  No darkening of the sample, no visible cathodoluminescence

* **Repeated acquisitions**
  12 x 50 s (=10 min) at different positions
  2 x 5 min (=10 min) at the same position
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
<figure><img src="image_18.png" /><figcaption>Spectra obtained at 1 kV – different positions</figcaption></figure>
Spectra obtained at 1 kV

<figure><img src="image_19.png" /></figure>

different positions

same position

5 minutes

10 minutes

<figure><img src="image_20.png" /></figure>

Intensity of peaks at 47 and 62 eV decreases: damaging of LiF, fluorine removal

Intensity of 49 eV shoulder and O Kα peak increases: oxidation of sample

Decrease of overall background intensity and of intensity of 55 eV feature:
no metal formation

Low energy shift of 90 eV feature: C Kα (n=3) ?
Comparison with synchrotron measurement

<figure><img src="image_21.png" /></figure>

Tsang (1987)

Intensity (arbitrary unit)

Background subtraction
0.5 eV shift

<figure><img src="image_22.png" /></figure>

2p-1s
emission band

core
exciton

Relative intensities
band / exciton
electrons / x-rays

<figure><img src="image_23.png" /></figure>

damaging under
electron excitation
occurs immediately
# Outline of the presentation

* Introduction – bibliography

* LiF electronic structure

* Experimental

* Results

* Conclusion
Conclusion

• Yes we can! We observe the Li Kα emission band of LiF

with minimal damages, but

○ Low intensity

o Large and changing background (cathodoluminescence)

o Poor spectral resolution

o Damages quickly appear (fluorine removal combined to oxidation)

o No more microprobe

• Observation of the core exciton – signature of the fluoride

• No charge effect

• No apparition of lithium metal

• To improve, work with

o cryostage

o acceleration voltages lower than 1 kV
Thank you!

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SORBONNE
UNIVERSITÉ

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