Quantum interference observed in state-resolved molecule-surface scattering
Data files
Jan 17, 2025 version files 230.74 KB
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data-archive-2024-10-18.zip
203.53 KB
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README.md
27.21 KB
Abstract
While the dynamics of collisions between a molecule and a solid surface are ultimately quantum mechanical, decohering effects owing to the large number of interacting degrees of freedom typically obscure the wave-like nature of these events. However, a partial decoupling of internal molecular motion from external degrees of freedom can permit striking interference effects to be manifest despite significant momentum exchange between the molecule and the bath of surface vibrations. We report state-prepared and state-resolved measurements of methane scattering from a gold surface which demonstrate total destructive interference between molecular states related by a reflection symmetry operation. High contrast interference effects prevail for all processes investigated, including vibrationally excited and vibrationally inelastic collisions. The results demonstrate the uniquely quantum mechanical effect of discrete symmetries in molecular collision dynamics.
README: Quantum interference observed in state-resolved molecule-surface scattering
https://doi.org/10.5061/dryad.g4f4qrg0j
Description of the data and file structure
Folders in the data archive correspond to particular subfigures from the main text and supplementary materials. README files for respective files are included within each folder.
Files and variables
File: data-archive-2024-10-18.zip
Description: This main folder consists of 8 sub-folders. The sub-folder consists of tabular data files and the corresponding README files.
- fig3d: each dataset corresponds to a particular tagging transition.
for each dataset there is generated two files:
* %%metadata.txt
* %%data.tsv
the data file contains (by column number):
1 : frequency offset of the tagging laser that is being tuned over a rovibrational transition
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
the metadata contains the following fields (by line number):
1 : tag vib level
vibrational quanta of lower tagging level
code:
0 : ground vibrational state ( v = 0 )
1 : v1 symmetric stretch fundamental
3 : v3 antisymmetric stretch fundamental
24 : v2 + v4 combination band (F2 symmetry)
2 : tag j
angular momentum quantum number j'' of lower tagging level
3 : tag sym
CH4 molecular symmetry group Td(M) classification of lower tagging level
To determine inversion parity of a level, use the following correspondance:
A1: P = -1
A2: P = +1
F1: P = +1
F2: P = -1
4 : tag branch
difference j' - j'' between upper tagging level angular momentum quantum number j'
and lower tagging level angular momentum quantum number j''
5 : tag level energy
energy of lower tagging level as quoted in CH4 HITEMP database (doi 10.3847/1538-4365/ab7a1a)
6 : tag database transition frequency
frequency of tagging transition as quoted in HITEMP.
7 : tag obseved transition frequency
frequency of tagging transition as observed in our bolometric tagging-based scattering measurements
8 : tag einstein coefficient
einstein coefficient of tagging transition as quoted in HITEMP
9 : pump vib level
vibrational quanta of upper pumping level [lower level is always 0 (v=0)]
10 : pump j
angular momentum quantum number j'' of lower pumping level
11 : pump sym
CH4 molecular symmetry group Td(M) classification of lower pumping level
for upper level symmetry, use following correspondance:
(lower) A1 -> A2 (upper)
A2 -> A1
F1 -> F2
F2 -> F1
12 : pump branch
difference j' - j'' between upper pumping level angular momentum quantum number j'
and lower pumping level angular momentum quantum number j''
13 : pump level energy
energy of lower pumping level from HITRAN database (doi 10.1016/j.jqsrt.2021.107949)
14 : pump transition frequency
frequency of pumping transition from HITRAN
15 : bolometer sensitivity timestamp
timestamp of creation of dataset (not included) of bolometer sensitivity measurements (BSM-DS).
bolometer sensitivity estimations only permit comparison of relative collisional transition
probabilities measured with in the same (BSM-DS). that is, relative collisional transition
probabilities should only be compared when their associated bolometer sensitivity timestamps
are identical. see doi 10.1063/5.0150009 for more on bolometer sensitivity correction method.
16 : bolometer sensitivity value
measured bolometer sensitivity for detector measurements under consideration
17 : incident kinetic energy
kinetic energy of incident molecular beam
18 : incident angle
angle formed between surface normal and the incident molecule beam
19 : scattering angle
angle formed between direction of scattered molecules being probed and surface normal.
at angle of specular scattering, scattering angle equals incident angle
20 : surface temperature
temperature of Au(111) surface
21 : lockin phase
rephasing of lockin output signals to obtain signal V(f) which is fit to determine relative transition probabilities, where:
f : lockin frequency offset
V(f) = Vx(f) cos(phi) + Vy(f) sin(phi), where:
Vx : lockin x
Vy : lockin y
phi : lockin phase
- fig4b: each dataset corresponds to a particular surface orientation (theta_i).
for the measurements presented in figure 4a, there is no pump laser.
the rovibrational levels populated in the incident molecular beam
that contribute to the scattered flux in the v=0 (Jf=6,Pi=-1) meta-CH4
rovibrational level probed consist of:
* >90% : v=0 (Ji=0,Pi=-1)
* <9% : v=0 (Ji=3,Pi=+1)
* <1% : all other levels
where the percentage indicates the fractional population in the incident beam.
for each dataset there are two files generated:
* %%data.tsv
* %%metadata.txt
the data file contains (by column number):
1 : tagging polarization angle
angle made between the tagging laser polarization and surface normal.
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
chronologically, a tagging laser frequency scan is first performed.
after the frequency scan is completed, the tagging laser
is tuned to the frequency of maximum absorption and then the
tagging laser polarization scan is performed.
information on the tagging transition:
* tag vib level : 0
* tag j : 6
* tag sym : A1
* tag branch : -1
* tag level energy : 219.94510 cm-1
* tag transition frequency : 2958.017263 cm-1
* tag einstein coefficient : 2.195E+01 s-1
other fixed parameters:
surface temperature : 300 K
kinetic energy : 210 meV
since the plotted polarization response curves R(theta_t)
are normalized, detector sensitivity factors were not measured.
the lockin x-y phase is 0.0 degrees for all datasets (i.e. only
the x channel is analyzed).
to compensate for the gradually decreasing bolometer sensitivity over
the course of the slow polarization scans, the raw data V(theta_n), where
theta_n denotes the nth measurement, are fit to the expression
v(theta) = sum(n=0,1,2) b_n cos(2n (theta-thetao)) d(theta;alpha)
where
d(theta;alpha) = (1 - alpha (theta-thetamin) / (thetamax - thetamin))
describes the bolometer sensitivity decay, with thetamin and thetamax being
respectively the first and last polarization angles measured.
the fit returns an estimation of the parameters b_0, b_1, b_2, thetao, and alpha.
we note that the best-fit values for the parameter alpha are consistent with independent
determinations of the long-term rate of bolometer sensitivity decay with exposure
to CH4.
the plotted results are that obtained by dividing the raw measurements V(theta_n) by the
factor b_0 d(theta_n;alpha).
the metadata file contains (indexed by row):
1 : theta_i
angle made between surface normal and direction of incident molecular beam
2 : theta_s
angle made between surface normal and direction of scattered molecular beam being probed
- fig4c: the measurements presented in figure 4c are in many respects identical to
those present in figure 4b. the differences are:
* theta_i is fixed at 35.0 degrees
* theta_s is fixed at 36.4 degrees
* there are two meta-CH4 rovibrational levels probed:
* v=0 (Jf=6,Pf=-1) (A1 symmetry)
* v=0 (Jf=6,Pf=+1) (A2 symmetry)
* the detection scheme employs the heterodyning technique described in
main text which acts to isolate the contribution from the state
v=0 (Ji=0,Pi=-1)
* see the data archive for fig2b for details on the pumping transition
for each dataset there are two files generated:
* %%data-freq.tsv
* %%data-pol.tsv
the data-freq file is the same format as the data file of the data files for figs 2 and 3
the data-pol file is the same format as the data file of the fig 4b data
the small offset is subtracted from the raw data before normalization. it is not clear to
us what the origin of this offset is, but the fact that it persists when the tagging laser
is tuned far off-resonance leads us to conclude that its subtraction is justified. to determine
the offset, the frequency scan (tabulated in the data-freq file) data at a fixed tagging
laser polarization are fit to a derivative-gaussian (i.e. FM) lineshape with constant offset
included as a fit parameter. no compensation for decaying bolometer sensitivity is attempted.
information on the tagging transitions:
* file prefix 00
* tag vib level : 0
* tag j : 6
* tag sym : A1
* tag branch : -1
* tag level energy : 219.94510 cm-1
* tag transition frequency : 2958.017263 cm-1
* tag einstein coefficient : 2.195E+01 s-1
* file prefix 01
* tag vib level : 0
* tag j : 6
* tag sym : A2
* tag branch : -1
* tag level energy : 219.91970 cm-1
* tag transition frequency : 2958.536362 cm-1
* tag einstein coefficient : 2.206E+01 s-1
other fixed parameters:
surface temperature : 300 K
kinetic energy : 210 meV
- figs2: each dataset corresponds to a particular tagging transition.
the tagging transitions are identical to those used in fig4c.
see the accompanying data archive for information on these tagging transitions.
these measurements use the same heterodyning technique of figs 2b and 4c.
see the data archive for 2b for information on the pumping transition.
fixed parameters:
incident angle theta_i : 25 degrees
incident kinetic energy : 100 meV
surface temperature : 300 K
for each dataset there is one file generated:
* %%data.tsv
with the file prefix %% key indicating the tagging transition:
* 00 : A1 symmetry [bolometer sensitivity of 31 (arb. units)]
* 01 : A2 symmetry [bolometer sensitivity of 27 (arb. units)]
the data file contains (by column number):
1 : scattering angle theta_s
angle made between the surface normal and the scattered angle being probed.
specular scattering corresponds to a scattered angle equal to the incident angle theta_i.
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
chronologically, a tagging laser frequency scan at fixed scattering angle is first performed.
after the frequency scan is completed, the tagging laser is tuned to the frequency of maximum
absorption and then the scan over scattering angles is performed.
the lockin x-y phase is 0.0 degrees for all datasets (i.e. only the x channel is analyzed).
- fig3b: each dataset corresponds to a particular tagging transition.
for each dataset there is generated two files:
* %%metadata.txt
* %%data.tsv
the data file contains (by column number):
1 : frequency offset of the tagging laser that is being tuned over a rovibrational transition
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
the metadata contains the following fields (by line number):
1 : tag vib level
vibrational quanta of lower tagging level
code:
0 : ground vibrational state ( v = 0 )
1 : v1 symmetric stretch fundamental
3 : v3 antisymmetric stretch fundamental
24 : v2 + v4 combination band (F2 symmetry)
2 : tag j
angular momentum quantum number j'' of lower tagging level
3 : tag sym
CH4 molecular symmetry group Td(M) classification of lower tagging level
To determine inversion parity of a level, use the following correspondance:
A1: P = -1
A2: P = +1
F1: P = +1
F2: P = -1
4 : tag branch
difference j' - j'' between upper tagging level angular momentum quantum number j'
and lower tagging level angular momentum quantum number j''
5 : tag level energy
energy of lower tagging level as quoted in CH4 HITEMP database (doi 10.3847/1538-4365/ab7a1a)
6 : tag database transition frequency
frequency of tagging transition as quoted in HITEMP.
7 : tag obseved transition frequency
frequency of tagging transition as observed in our bolometric tagging-based scattering measurements
8 : tag einstein coefficient
einstein coefficient of tagging transition as quoted in HITEMP
9 : pump vib level
vibrational quanta of upper pumping level [lower level is always 0 (v=0)]
10 : pump j
angular momentum quantum number j'' of lower pumping level
11 : pump sym
CH4 molecular symmetry group Td(M) classification of lower pumping level
for upper level symmetry, use following correspondance:
(lower) A1 -> A2 (upper)
A2 -> A1
F1 -> F2
F2 -> F1
12 : pump branch
difference j' - j'' between upper pumping level angular momentum quantum number j'
and lower pumping level angular momentum quantum number j''
13 : pump level energy
energy of lower pumping level from HITRAN database (doi 10.1016/j.jqsrt.2021.107949)
14 : pump transition frequency
frequency of pumping transition from HITRAN
15 : bolometer sensitivity timestamp
timestamp of creation of dataset (not included) of bolometer sensitivity measurements (BSM-DS).
bolometer sensitivity estimations only permit comparison of relative collisional transition
probabilities measured with in the same (BSM-DS). that is, relative collisional transition
probabilities should only be compared when their associated bolometer sensitivity timestamps
are identical. see doi 10.1063/5.0150009 for more on bolometer sensitivity correction method.
16 : bolometer sensitivity value
measured bolometer sensitivity for detector measurements under consideration
17 : incident kinetic energy
kinetic energy of incident molecular beam
18 : incident angle
angle formed between surface normal and the incident molecule beam
19 : scattering angle
angle formed between direction of scattered molecules being probed and surface normal.
at angle of specular scattering, scattering angle equals incident angle
20 : surface temperature
temperature of Au(111) surface
21 : lockin phase
rephasing of lockin output signals to obtain signal V(f) which is fit to determine relative transition probabilities, where:
f : lockin frequency offset
V(f) = Vx(f) cos(phi) + Vy(f) sin(phi), where:
Vx : lockin x
Vy : lockin y
phi : lockin phase
- fig3c: each dataset corresponds to a particular tagging transition.
for each dataset there is generated two files:
* %%metadata.txt
* %%data.tsv
the data file contains (by column number):
1 : frequency offset of the tagging laser that is being tuned over a rovibrational transition
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
the metadata contains the following fields (by line number):
1 : tag vib level
vibrational quanta of lower tagging level
code:
0 : ground vibrational state ( v = 0 )
1 : v1 symmetric stretch fundamental
3 : v3 antisymmetric stretch fundamental
24 : v2 + v4 combination band (F2 symmetry)
2 : tag j
angular momentum quantum number j'' of lower tagging level
3 : tag sym
CH4 molecular symmetry group Td(M) classification of lower tagging level
To determine inversion parity of a level, use the following correspondance:
A1: P = -1
A2: P = +1
F1: P = +1
F2: P = -1
4 : tag branch
difference j' - j'' between upper tagging level angular momentum quantum number j'
and lower tagging level angular momentum quantum number j''
5 : tag level energy
energy of lower tagging level as quoted in CH4 HITEMP database (doi 10.3847/1538-4365/ab7a1a)
6 : tag database transition frequency
frequency of tagging transition as quoted in HITEMP.
7 : tag obseved transition frequency
frequency of tagging transition as observed in our bolometric tagging-based scattering measurements
8 : tag einstein coefficient
einstein coefficient of tagging transition as quoted in HITEMP
9 : pump vib level
vibrational quanta of upper pumping level [lower level is always 0 (v=0)]
10 : pump j
angular momentum quantum number j'' of lower pumping level
11 : pump sym
CH4 molecular symmetry group Td(M) classification of lower pumping level
for upper level symmetry, use following correspondance:
(lower) A1 -> A2 (upper)
A2 -> A1
F1 -> F2
F2 -> F1
12 : pump branch
difference j' - j'' between upper pumping level angular momentum quantum number j'
and lower pumping level angular momentum quantum number j''
13 : pump level energy
energy of lower pumping level from HITRAN database (doi 10.1016/j.jqsrt.2021.107949)
14 : pump transition frequency
frequency of pumping transition from HITRAN
15 : bolometer sensitivity timestamp
timestamp of creation of dataset (not included) of bolometer sensitivity measurements (BSM-DS).
bolometer sensitivity estimations only permit comparison of relative collisional transition
probabilities measured with in the same (BSM-DS). that is, relative collisional transition
probabilities should only be compared when their associated bolometer sensitivity timestamps
are identical. see doi 10.1063/5.0150009 for more on bolometer sensitivity correction method.
16 : bolometer sensitivity value
measured bolometer sensitivity for detector measurements under consideration
17 : incident kinetic energy
kinetic energy of incident molecular beam
18 : incident angle
angle formed between surface normal and the incident molecule beam
19 : scattering angle
angle formed between direction of scattered molecules being probed and surface normal.
at angle of specular scattering, scattering angle equals incident angle
20 : surface temperature
temperature of Au(111) surface
21 : lockin phase
rephasing of lockin output signals to obtain signal V(f) which is fit to determine relative transition probabilities, where:
f : lockin frequency offset
V(f) = Vx(f) cos(phi) + Vy(f) sin(phi), where:
Vx : lockin x
Vy : lockin y
phi : lockin phase
- fig3a: each dataset corresponds to a particular tagging transition.
for each dataset there is generated two files:
* %%metadata.txt
* %%data.tsv
the data file contains (by column number):
1 : frequency offset of the tagging laser that is being tuned over a rovibrational transition
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
the metadata contains the following fields (by line number):
1 : tag vib level
vibrational quanta of lower tagging level
code:
0 : ground vibrational state ( v = 0 )
1 : v1 symmetric stretch fundamental
3 : v3 antisymmetric stretch fundamental
24 : v2 + v4 combination band (F2 symmetry)
2 : tag j
angular momentum quantum number j'' of lower tagging level
3 : tag sym
CH4 molecular symmetry group Td(M) classification of lower tagging level
To determine inversion parity of a level, use the following correspondance:
A1: P = -1
A2: P = +1
F1: P = +1
F2: P = -1
4 : tag branch
difference j' - j'' between upper tagging level angular momentum quantum number j'
and lower tagging level angular momentum quantum number j''
5 : tag level energy
energy of lower tagging level as quoted in CH4 HITEMP database (doi 10.3847/1538-4365/ab7a1a)
6 : tag database transition frequency
frequency of tagging transition as quoted in HITEMP.
7 : tag obseved transition frequency
frequency of tagging transition as observed in our bolometric tagging-based scattering measurements
8 : tag einstein coefficient
einstein coefficient of tagging transition as quoted in HITEMP
9 : pump vib level
vibrational quanta of upper pumping level [lower level is always 0 (v=0)]
10 : pump j
angular momentum quantum number j'' of lower pumping level
11 : pump sym
CH4 molecular symmetry group Td(M) classification of lower pumping level
for upper level symmetry, use following correspondance:
(lower) A1 -> A2 (upper)
A2 -> A1
F1 -> F2
F2 -> F1
12 : pump branch
difference j' - j'' between upper pumping level angular momentum quantum number j'
and lower pumping level angular momentum quantum number j''
13 : pump level energy
energy of lower pumping level from HITRAN database (doi 10.1016/j.jqsrt.2021.107949)
14 : pump transition frequency
frequency of pumping transition from HITRAN
15 : bolometer sensitivity timestamp
timestamp of creation of dataset (not included) of bolometer sensitivity measurements (BSM-DS).
bolometer sensitivity estimations only permit comparison of relative collisional transition
probabilities measured with in the same (BSM-DS). that is, relative collisional transition
probabilities should only be compared when their associated bolometer sensitivity timestamps
are identical. see doi 10.1063/5.0150009 for more on bolometer sensitivity correction method.
16 : bolometer sensitivity value
measured bolometer sensitivity for detector measurements under consideration
17 : incident kinetic energy
kinetic energy of incident molecular beam
18 : incident angle
angle formed between surface normal and the incident molecule beam
19 : scattering angle
angle formed between direction of scattered molecules being probed and surface normal.
at angle of specular scattering, scattering angle equals incident angle
20 : surface temperature
temperature of Au(111) surface
21 : lockin phase
rephasing of lockin output signals to obtain signal V(f) which is fit to determine relative transition probabilities, where:
f : lockin frequency offset
V(f) = Vx(f) cos(phi) + Vy(f) sin(phi), where:
Vx : lockin x
Vy : lockin y
phi : lockin phase
- fig2b: each dataset corresponds to a particular tagging transition.
for each dataset there is generated two files:
* %%metadata.txt
* %%data.tsv
the data file contains (by column number):
1 : frequency offset of the tagging laser that is being tuned over a rovibrational transition
2 : lockin x
component of lockin amplifier output that is in-phase with the reference clock.
lockin amplifier receives bolometer detector amplifier output as input signal.
3 : lockin y
component of lockin amplifier output that is 90 degrees out-of-phase with the reference clock
the metadata contains the following fields (by line number):
1 : tag vib level
vibrational quanta of lower tagging level
code:
0 : ground vibrational state ( v = 0 )
1 : v1 symmetric stretch fundamental
3 : v3 antisymmetric stretch fundamental
24 : v2 + v4 combination band (F2 symmetry)
2 : tag j
angular momentum quantum number j'' of lower tagging level
3 : tag sym
CH4 molecular symmetry group Td(M) classification of lower tagging level
To determine inversion parity of a level, use the following correspondance:
A1: P = -1
A2: P = +1
F1: P = +1
F2: P = -1
4 : tag branch
difference j' - j'' between upper tagging level angular momentum quantum number j'
and lower tagging level angular momentum quantum number j''
5 : tag level energy
energy of lower tagging level as quoted in HITRAN database (doi 10.1016/j.jqsrt.2021.107949)
6 : tag transition frequency
frequency of tagging transition as quoted in HITRAN
7 : tag einstein coefficient
einstein coefficient of tagging transition as quoted in HTIRAN
8 : pump vib level
vibrational quanta of upper pumping level [lower level is always 0 (v=0)]
9 : pump j
angular momentum quantum number j'' of lower pumping level
10 : pump sym
CH4 molecular symmetry group Td(M) classification of lower pumping level
for upper level symmetry, use following correspondance:
(lower) A1 -> A2 (upper)
A2 -> A1
F1 -> F2
F2 -> F1
11 : pump branch
difference j' - j'' between upper pumping level angular momentum quantum number j'
and lower pumping level angular momentum quantum number j''
12 : pump level energy
energy of lower pumping level
13 : pump transition frequency
frequency of pumping transition
14 : bolometer sensitivity timestamp
timestamp of creation of dataset (not included) of bolometer sensitivity measurements (BSM-DS).
bolometer sensitivity estimations only permit comparison of relative collisional transition
probabilities measured with in the same (BSM-DS). that is, relative collisional transition
probabilities should only be compared when their associated bolometer sensitivity timestamps
are identical. see doi 10.1063/5.0150009 for more on bolometer sensitivity correction method.
15 : bolometer sensitivity value
measured bolometer sensitivity for detector measurements under consideration
16 : incident kinetic energy
kinetic energy of incident molecular beam
17 : incident angle
angle formed between surface normal and the incident molecule beam
18 : scattering angle
angle formed between direction of scattered molecules being probed and surface normal.
at angle of specular scattering, scattering angle equals incident angle
19 : surface temperature
temperature of Au(111) surface
20 : lockin phase
rephasing of lockin output signals to obtain signal V(f) which is fit to determine relative transition probabilities, where:
f : lockin frequency offset
V(f) = Vx(f) cos(phi) + Vy(f) sin(phi), where:
Vx : lockin x
Vy : lockin y
phi : lockin phase